yeah, in the base game you really need trashing and +buy for village/smithy to be good. the +buy isn't even so important for the double-province turns - you want it in the early-mid game so you can buy multiple engine pieces at once. without that, you typically can't build quickly enough.
attacks like witch & militia also favor engines over BM...discard attacks in particular are nasty for any BM strat, since it's really hard to buy a province with just 3 cards.
altogether, that's a lot of pieces that need to be in place for the engine to win (even considering that you could get by without, say, an attack). and base dominion is especially short on villages, good trashing, and good attacks. this is why so many people still think dominion is a big money game period, because the base game largely is