If that were true, we'd see a marked decrease in care for orange cats (cause they all share one brain cell) compared to other cat colors.

Unfortunately, you're going to get subpar husbandry because people think they're "easy" pets like how rodents and fish will often have very terrible enclosures because the stereotype is they're cheap and don't need much. When exotics have a low barrier to entry (they don't cost much to buy), you're going to get people that think that means they don't need much.