They really emphasise proposals have a very specific theme or angle. I could easily just pick an album and review every song for 90 pages and put a bit of filler in there about other random thoughts. but that would be rejected by them because it's boring. There has to be some sort of additional thesis there. And I just don't know what album I feel that strongly about in a unique way that hasn't already been covered.
Those are all great bands I could choose from. I'd love to read one about an of Montreal album, but I don't think I know enough about Kevin Barnes behind the scenes to be able to talk about them with any authority.
Ween and Weezer have already had books (xtc too maybe, i'm not sure). Though there's nothing stopping anybody from writing about different albums from the same band, it feels like you're less likely to be chosen.
Bands that I have internalized enough that I think I could write a book about them, hmmm. Rush, Barenaked Ladies, Ween, Phish, XTC, Genesis, Jellyfish, maybe a handful of others. But I don't know what my thesis would be other than "i like this here is why".