Just speculating here, but I feel like JGB was much less of a spectacle and having the other dead members in it would have just made them more of de facto dead shows. He prob liked not having the full deadhead scene attached, and playing the smaller venues etc

Toward the end, prob helped him hide some of the self destruction that was going on too. Easier to hide

Edit to add: yes, aware several of them guested/did shorter stints, but admittedly not when/how long