Say we have 3 basic decks on a board: draw deck (e.g. Madman), BM-Attack, and X. It is entirely possibly to set up a scenario where BM-attack > X > Madman > BM-attack. Without the attack, you'd skip on a Madman deck (e.g. Coppersmith/Madman/+buy/coppers) against a decent engine setup (say Library/Spice merchant/Festival), but the engine can be utterly destroyed by junkers (e.g. Mountebank) and top deck muckers (E.g. mass Rabble). It takes relatively little junking/top deck mucking to lower the odds of connecting +buy and +cards so that engines falter (e.g. an Engine with 1/4 cards as +action and 1/4 cards as +3 cards needs just 5 or so curses to have terrible of odds of fully firing); one additional Madman, on the other hand, can draw another 40 cards (the bigger issue is waiting a turn or two longer until you hit a hand with 2 Madmen in it). Similarly, Counting house is a terrible play against a lot of strats, but if your deck is getting massively bloated (say with lots of copper/estates from Amb in 4er), it becomes a LOT more powerful if you can do something like Village -> Chouse -> Cellar to draw out all your megaturn cards (say Squires and Bridges).
Megadraw is often very, very slow to setup, but if you've been nuking each other's decks, you gain the time needed and you often don't care about deck top ordering. On the flip side, megadraw can be really, really weak against trashing attacks. For instance, if you are going for Madmen, Swindler is truly evil. Both Hermit -> Silver (or worse) and Madman -> Curse (copper) depletes the Madmen you can gain (barring trash diving), you can set up your entire deck & lose ... as you have no way to get enough Madmen once you've been trashed hard enough. Other trashing, like Knights or Sab, also can hurt a lot. When you need every action card, any time an action card goes into the trash you lose at least half a turn. Likewise, discarding attacks can slow you down.
Or take something like using Inn to setup a big Bridge turn. It takes a lot of turns to get all the Bridges you will need and longer yet to get them all in the discard at the right time. However, if you have been Mountebanking, you likely will have a lot of $4 & $5 hands before a shuffle and the other guy cannot quickly nab 5 provinces.
So, yes I'd say that megadraw options like Madmen, Nv, and maybe some other odd ducks (like Chouse, Apprentice, Xroads) are strategies that are defensive. They get relatively stronger when decks are filled with crud.
Kc/Scheme/X likewise suffers from the curse of a slow burn. Getting the big setup - two Kc, two Sch, and some other power card, then lining them all up takes time. While I'm futzing around buying all of that you might just do something like quickly grab 4 Provinces and then start piling the Duchies. Now X has to be something really good to not be the attack itself, but they you don't care at all about trashing (your 5 power cards are always in hand), junking (your 5 power cards ensure you have no really bad hands), and only a bit about top deck mucking. On the other hand, discard attacks (particularly Minion) are brutal. Something truly horrid (like Kc/Kc/Sch/Sch/B-crat) can become insanely strong if you have the time to build out to it (e.g. 4er with Amb). Certainly the strengths of this type of deck differ greatly from cards that just let you discard junk of deck top (like Cartographer). Something simple like Procession/Armory/Useful $5 does not care if you are getting cursed - it will keep giving you a new Prssn/ replaced Arm on top and a nice shiny new $5. Discarding actually hurts more (because the odds of you getting a Silver or something useful out of 2-3 other cards is much higher than out of 1) than junking here.
Because these setups can shrug off the attacks and competing strategies often can't that makes them more powerful than they be without the attacks on the board. Certainly the top deck control category is overly broad.
