Umm.. can you provide examples of this?
Sure. Florrat already covered the gist of it, but here's some more:
Treating card draw as effective treasure amounts, I don't really see how that is possible
Treating card draw as effective treasure amounts is an acceptable approach only when you consider Big Money strategies, that is, when you ignore almost everything Dominion is really about.
The usual pattern of building an engine is to first get rid of most if not all of your junk (starting Coppers and Estates), then work on your draw until you can reliably draw your deck each turn, and then start improving your buying/gaining power. In practice you can't always follow this pattern of course, e.g. if the only trasher is Forge, you have to invest in some economy first; if it's Mint you want some good draw to trash a lot of Coppers at once, but the general pattern shows why early buying power is a very poor indicator of anything.
An example game where I trash down to only 6 cards after T8, at which point my only buying power comes from a Market and a Count. I proceed to gain a whole bunch of stuff (including Duchies for VP) by developing Fortresses, and the only real "buying power" I eventually amass is but an unfortunate side-effect of playing a Pillage each turn, for Spoils are not much better than Curses in a Double-Tactician engine. If you'd do a buying-power/turn analysis, my strategy would be judged as really awful, yet it worked out pretty good
Another example, here I go for some early buying power because I want the Forge, but then I trash down to only $4 buying power halfway T12, after which I bring it back up to $8. I could actually build it quite a bit further, say, to $16. A "buying power" analysis would conclude that this is better, but it's not: due to the lack of +buy, 16 is as good as 8. Furthermore, such an analysis would also say that a strategy that does not use 2 Forges to trash Fortresses into Provinces but does get to 8 a little faster is better, yet it clearly isn't.
These aren't exceptions, they are specific examples of the general rule that in actual high-level Dominion play Big Money strategies (and hence BM-focused analysis as well) are usually irrelevant. The only reason they feature prominently in discussions on this forum (particularly when simulation is concerned) is that they are very easy to learn, and for beginners they are thus a great way to quickly improve their play (which until then consisted mostly of "buy the shiniest card you can afford"), and for simulators they are easy to implement. If, however, you've been playing Dominion for more than a few weeks, or you've progressed beyond your first "hello world, look at me, I can play Big Money!" strategy in a simulator, their only use is as a baseline against which to compare other strategies, for if your envisioned strategy can't even beat Big Money, you can dismiss it right away.