That, and I think everyone who says that has already used multiple other resources. So, their knowledge base is a lot more broader than what it seems. And moreover, I think if you look at FA by itself, it's garbage even with first two years of med school, because all it is is just facts. But, after you've recently reviewed material in other sources, it seems as if everything is in FA, because in reality, it probably does have everything you really need, but you won't be able to retain it nor make something out of it without having read in a more detailed applicable manner. Like, that one important line that you need to answer the question may be in FA, but it's useless becuase it's so hard to just look at it independently and retain it AND more importantly, APPLY it to what they're asking. But, after having done all the reading/reviewing, that one line "makes sense" because you have the recently aquired background to make that line hihglight in your brain. I don't know, just my two cents. That's the way I feel using FA. I remember I looked at it in th beginning, and it was useless because if i read something in it, i'd either forget it, or would have to read more elsewhere to make use of that line.
All my friends who have done really well, in reality, only used FA in their last 2 weeks as a final review, and at that point, I can see where FA can be very useful becuase you can make sense of all those nit picky facts that you have read everywhere else. So, I think, that line "FA is all you need", or "memorize FA" is VERY skewed...take that with a grain of salt obviously. And, "memorizing FA" is really impossible, IMHO, without at least having other knowledge. Otherwise, it's like memorizing arrow up, arrow down, to the right, to the left, etc. You get the point.