Back then you had guys like lex steele and justin slayer owning their own companies. Wonder what happened because black porn has been died for the longest. Now you do have some black companies like pinky and cherokee da ass but nothing really noticable.There'a a lot wrapped up in that subject. Porn has been about racial stereotypes for a very long time. Hence the obsession with "BBC" and submissive Asians. Actors gladly accept the stereotypes because it's a paycheck.
As for why non-white ppl don't start their own studios, I'd say it comes down to capital. Black ppl generally don't approve of porn because of our socially conservative culture. That said, any Black performer would have no reservations starting a porn studio but they don't have access to the money needed.
Separate issue have you found that being able to be classified as white has become harder. Was going down the list of best newest pornstars from latina, black, and asian. One thing noticed is alot of the older stars from black and asian are gone but on the latina list there was a few still active. Now could it be they was able to be classified as white back then because for the longest they was more popular than the Asian stars. But now it seem the asians are more popular than them.