The only place this kind of favoritism is a negative is with personal relationships. Nobody bats an eye when the riser is a fraternity or alma mater cohort, where that kind of thing is expected.

If I were a betting man, I'd say it's a class argument that the favoritism wasn't "earned" in the proper way, without the old school tie.

Aside from that, in contemporary business culture, losing respect of your peers is no loss when you're upwardly mobile. They're the ones you're leaving behind.

I suspect that you're projecting here. I think favoritism in any of those situations is both expected and resented.

I don't see how sexual relationships are any less class-based than alma mater or frat stuff. People are more likely to have been in the same frat with someone outside of their class than to have dated someone outside of their class.

There are lots of token and outsider members of colleges and frats that the insider groups will never even notice. The person dating the boss or the bosses' daughter/son is more likely to be a member of an insider group than somebody who attended the same elite university at the same time - especially if the frat/college person is of a different race or economic class than the boss.

Went to the same school, in the same frat, from the same town, went to the same camp, dated your sister once are all shorthand for describing insider groupings, not the cause of them.

People who work hard who are not insiders in that way will resent it.