What company still promotes its workers? Who does that? That's a discrimination lawsuit waiting to happen. Because, why did you promote HIM and not me? Is it because I is black? Why Kevin and not Max? Worse, why Kevin and not Maxine?
What company wants to navigate that minefield? It's far easier to just hire someone new for a leader position. For multiple reasons. First, the one stated above. This is someone who was really, really qualified, independent of their race, gender, sexual preference, religion or choice of car. No, you can't see their qualification, sorry, because uh... privacy regulations. Second, nobody in the team is getting distinguished. Everyone's the same. Everyone's equally valuable to the company. Warm fuzzy feelings all around. And finally, none of you DESERVE a promotion, just be glad we don't fire you so don't you DARE ask for a raise!