The elite players bit is another huge thing killing the boards. It used to be a newb could come in say I think this is good and then people would debate on theoretical merit. Elite players have gotten good enough that, pretty much they can win with anything against non-elite players. The tacit skills of timing, adaptation, and end game strategy are now more than enough that elite players could be utterly terrible with some card or even class of cards, but their execution of a slightly weaker strategy is flawless (or close thereto) and will trump the idealized strengths of cards and combos. This leads to the boards becoming moribund. When arguments start getting made based on ranking it becomes really hard to delve into the subtle parts of the game; someone who executes better can just shut down a thread without actually addressing the dynamics in question. Coupling this with the heavy frequency bias and there just isn't a lot to talk about.
I don't believe that "elite players" are "utterly terrible" at anything. You don't become an elite player through memorizing 29384729384729837 different cool tricks you can do in different situations, and then lose games because your opponent used that one trick you didn't remember. You become an elite player through understanding how the entire game works as a whole (not perfectly of course, but on a certain level). When you're good at estimating the consequences of your actions in general, there won't be "some card or even class of cards" that you're "utterly terrible" at.
FWIW, I played Hermit/Market Square against Marin who had just returned and didn't know about the combo, he won that game.
See this is the sort of thing I'm talking about, I say they could be terrible and immediately you start as though I actually ever said such. This was a rhetorical contrived case to illustrate a point. And yes it does happen a lot that elite players do miss things because they have certain biases for and against things.
Dominion isn't about learning 1001 tricks, but learning about the tricks, particularly the less obvious shades of value are one way to "get an understanding" of how the game works. Take the long Counterfeit/Venture thread that was recently revived, the "trick" of Counterfeit being the strongest single copper trasher in a Venture deck is pretty weak. But the logic behind why Counterfeit works well when you are already committed to Venture is the type of "understanding" that lets you learn the game. Sure sitting down to crank numbers and the like isn't time effective, but the process of understanding where to find "tricks" is pretty good for learning board reading. Once you have a tacit feel for the game you could, theoretically, be utterly terrible at playing Venture decks, but odds are even when Venture is the strongest option, elite players could still win with something else; even when they lose it is awfully hard to see if they were wrong or just unlucky.
Now are elite players going to be actively bad? No. But there are things where they just have a good feel and the margin by which they are wrong isn't strong enough to swamp their tacit skill level. Think of this way, if I pick a better base strategy, just how much better does it have to be before I can beat someone with better sense of game flow and the like? Pretty high. Most of the interesting stuff about dominion is now going have less than 5% chance of swinging a game. Pick a card, even a strong on like Pool or Steward; try playing without buying it ever for a 100 games. How many extra will you lose? Not that many.
And this is the thing that kills actual Dominion discussion here, the stuff that isn't well mapped out is rare enough that even if, by some miracle, the elite players were completely ass-backwards about some card it wouldn't show up much in the stats. So for now, we've reached a point where the most efficient way to become an elite player is just to play a bunch and the interesting questions are actively killed on the board.
No, you don't get an understanding of how the game works by learning individual things that only apply in specific scenarios. You get an understanding of how that individual thing works in that specific scenario. I stopped reading the Counterfeit/Venture thread when the posts got tl;dr, so I'm not sure what kind of stuff was discussed there, but I'm sure that learning about "when cards dig for stuff, it's good to build your deck in such a way that they will hit stuff you want them to hit" is way more useful than learning about "Counterfeit is good with Venture". If you learn the first thing, you already know that you want lots of cantrips when Golem is your only splitter, you want as few non-Action cards as possible when Scrying Pool is your only draw, you don't want Estates when you're playing Rebuild and the Duchies are out, and a bunch of other stuff that will actually be useful in real games. You can say that these things are obvious, but it's not obvious
how important it is to not have Estates with Rebuild, or to have lots of cantrips with Golem. I know I shouldn't have too many non-Action cards with Scrying Pool, but I really want to hit $5 so should I buy this Silver anyway? If I have a general understanding of how the game works, I can probably tell if it's worth it or not depending on the kingdom, but if I know how good Counterfeit is with Venture, that doesn't help me at all in that situation.
Also, even though we are all Wandering Winder, elite players are, surprisingly enough, actually not a hive mind. Everyone has their own playing style and it influences things, and some elite players are simply even better than some other elite players and that also influences things. I remember a lot of games where I went for a different strategy than my opponent, and one of us won because we both implemented our strategies fairly well and one strategy was better than the other. I don't remember a lot of games where I went for a different strategy than my opponent and felt that the winner had the worse strategy, but played it so much better that he won anyway. The majority of time, I'm probably going for the same strategy as my opponent, but there are times when someone tries out something new. It might be the case that there's stuff that you would try out, but an elite player wouldn't, and then we don't have data about elite players trying it out, but I'm not buying it that there's any major reason for this other than that the strategy actually isn't very good and elite players can see it without even having to try.
If you pick a strong card like Scrying Pool and ignore it for 100 games, you will probably lose pretty much all the games where the card is on the kingdom. Which
is not that many. And if you would have lost somewhere around 50% of those games anyway, it's just natural that you won't lose that many extra games because there aren't that many extra games that you could have possibly lost in the first place. Maybe there's one or even two games where ignoring Pool is actually correct, but most of the time, it won't be, and if you ignore it regardless, there's just no way you're ever winning the game against someone who doesn't.
It's not a bad thing to ask questions on the forums. People will answer the questions and you can learn something from that. If you refuse to learn, that's your own problem, not the forum's.