They should do a qualifier system like the other combat sports rather than have this lineage stuff. It's too subjective and political.
I agree that not just anyone should be allowed to step into the black belt division at the Worlds. However, there are also plenty of legitimate black belts who still probably shouldn't qualify to compete against guys like Roger Gracie, Marcelo Garcia, etc. It'd be better to have a qualification system where you have to earn points by winning smaller IBJJF events in order to earn a spot at the Worlds.
Of course, then the IBJJF wouldn't make tons of money off the 100+ competitors in each bracket for the lower belts which is probably why they don't do this, but it would result in a better tournament for the elite guys.