I do not remember anything that would indicate that orcs selected leaders or anything else based on merit.

Parts that were shown included plenty of violence, treachery, oppression including slavery and other mistreatment (all included also orcs as victims).

With basically no reward for merit.

> All the good-guy societies are deeply hierarchical.

Yes, but the same is true for evil ones.

And if anything, good guys have less extreme hierarchies. Especially hobbits.