I wouldn’t necessarily draw a parallel between a fatwa and an indulgence. An indulgence is more along the lines of a quid pro quo, and both parties are generally happy with the outcome.
Fatwas seem to be more along the lines of a “Dear Achmed” advice column or call in show. When anyone and everyone can be an authority, no one is an authority.
This decentralization of authority seems to spawn some very strange crackpot groups and ideas, which has probably contributed to the tribal “us vs. them” mentality you see all over the Middle East.