Sigmund Freud just said a lot of random stuff with essentially no evidence to back it up, all of which has, unsurprisingly, been refuted in recent decades.
The existence of emotionally immature individuals of limited intelligence does not prove his theory. If anything Freuds own life experiences should have taught him that some people just love to hate. Perhaps if they had received the necessary therapy at a young age they may have turned out differently, but that would have required both them and their legal guardians to actually respect therapy as an idea, and we know that they wouldn’t have done.
Perhaps that’s really the ultimate problem, everyone can suffer personality disorders but it’s only those from crap upbringings that allow them to propagate into adulthood, everyone else gets the help they need.