It doesn't just undermine the self-esteem of a PoC, it undermines the self-esteem of white folks, too. Hiring or promoting people due to their skin color is just wrong, no matter what skin color that is. As a white dude, seeing my PoC teammates in the past celebrated not for their accomplishments, but for something they had no control over (their skin color) is sad.
"John in Engineering is really talented, and works his tail off daily. He has come up with some really ingenious solutions to tough problems that have allowed us to grow as a company....but we're celebrating him because he's black, not because he's a kickass engineer". Seen things like this before, which make no sense. Celebrating an employee who is awesome at their job for being awesome at their job is great. You're a company, after all, not a social club. The goal is to grow and make money. Celebrate anyone who can do help with that, regardless if they are black, white, yellow, orange, green, pink, whatever.
Diversity is cool, but when it's put into practice and not shouted from the rooftops, it's even better.