I'm going to say it's a combination of both.
When Fighters were allowed to have their own sponsors, they made that extra money needed to support themselves, their coaches, and their families.
When Fighters were, let's be honest here, "allowed" to juice(just don't get caught) without USADA, we more often than not had fights between fighters we WANTED to see and not watch replacements.
Hell..without USADA, Vitor Belfort would still have a career, Hendricks will still fool everyone into believing he's a top-level fighter, Chael Sonnen would still be here, and Brock Lesnar would have been scheduled to take on [insert next opponent] on such and such date.
Oh and Mark Hunt won't be whining at all and attacking people in facebook(or whatever he uses)....