To be honest, this sounds pretty much like the same process as Google, with the main significant difference being that the promotion is approved by committee. But even then the purpose of that would seem to be exactly the same as your statements "Managers then all get together and level set on performance and promotions. Managers have to defend a promo and performace with data." It's just done with more formality at Google due to their size and desire for equitable treatment across teams.
