For Halo: Infinite, assuming it has a ranking system / division system similar to Halo 5.
I think it would be cool if there was an aspect to your service record that showed all your past season ranks of each playlist, instead of only your current season rank like Halo 5.
The rank you finished the season with also, not the highest rank you achieved that season. Also gives people more of an incentive to play.
Plus it might give people more of an incentive to play on their actual account rather than smurf.