Genuine question, but I f you’ve never worked under that type of system, why the strong opinion shouting it down
You don't have to have worked under a system to see its inherent unfairness, as I said, FO's are not taking the upgrades because of the inequities of the seniority system. Used to work for an organisation where physical floggings were part of the discipline system that could be imposed by the captain in the old days, for some unknown reason it's no longer permitted.
I'm sure there are managers about who would love to see its reintroduction, for productivity reasons you understand.