Yeah. Basically Cersei's conversation with Joffrey in Season 1 when he was speaking of raising a personal army and she pointed out "why would they fight for you against their home?" was on point.

At this point why is anyone who isn't a Lannister or beholden/dependent upon the Lannisters and Lannister largesse going to fight against their own interests?

However, not for nothing, the Lannisters are extremely rich, and that's not to be sneezed at.