As a Compilation Hater I'll answer your question. Advent Children also add twists to the FFVII plot; however those who accept The Compilation don't seem to notice that too often. This is probably due to Dirge of Cerberus' vast amount of retcon even when compared to the rest of The Compilation. I must admit, Advent Children look ace and it is fun to watch. But I like the original plot of FFVII more and so choose to put AC together with the rest of the spin-offs.
And what about the UOG? It exist only to explain what wasn't explained in the game. But Compilation Haters still ignore it, believing more in their own theories, than in the word of SE.
Example:
Originally Posted by Psi
Jenova was the real villain, and Sephiroth was just being her bitch.
Completely wrong, as proved by the UOG. But some people still ignore the book without any reason.
maby people like what they think better
Forever obsessed with the one and only flower girl <3