Someone else might think they're really good. That someone else might themselves be incompetent, but might also have people who think they're good. This gets l

Someone else might think they're really good. That someone else might themselves be incompetent, but might also have people who think they're good. This gets less likely as the relationship graph grows, but I don't think people are good at judging competence without widely recognized and respected metrics. This is why getting friends and connections is a powerful strategy, because many fields are not interested in establishing fair gatekeeping. And for some very difficult roles, it's way easier to make friends than to be competent. This is made all the more difficult when competence is a quickly moving target. The positive referral is a rarely moving target though.