On the other side of the spectrum, consider Forge. Forge can be a stronger trasher in the mid-game as opposed to the early game (suppose there's Tactician or something like that)
If I could afford Forge before the first shuffle, I'd buy Forge before the first shuffle. I think the only reason we don't see how great it is as an early trasher is that we never have it to try out.
This is a fair point, and I agree with you. But I wasn't trying to make an argument about Forge, just about what conclusions you might draw after playing with a card a bit that may or may not generalize. Sometimes, a late Forge can get you thin quickly and that could be the way to go on a particular board, but it would be incorrect to draw the conclusion that later trashing is a good idea in general. Maybe it was a bad example because the conditions are not usually right for Forge, but it was the first thing that came to mind.
The comment in the article was that Sentry demonstrates that early trashing is important
more than most other trashers do. I don't think this is true, since most trashers demonstrate this clearly enough. It would be more difficult to find a decent trasher that doesn't demonstrate that. You just often don't see the disparity when both players can always open with the trasher. New players might not do that, but they could eventually learn that an early Steward is good, or an early Remake is good, or an early Chapel is good when their opponents open with them, quickly get lean, efficient decks, and win. Of course, Sentry can be a fast trasher, so it makes this same point. Everyone gets to see this disparity in action on Sentry, because you can't always open with it, and there's a power level difference based on when you get it. But the power level difference of Sentry based on when you get it is not really generalizable to trashing in general, so "early trashing is good" and "early Sentry is good" get muddled a bit, that's all.