[GocartMozart]

because there are tertiary reasons why someone would pick to have 7 people on a bench. who knows why they picked them and if they truly did have a bias towards the top of the league, or if that had anything to do with it. that's all speculative. Rather I'm trying to give counter arguments to why I'd rather have a smaller bench, and in particular show that it is to the disadvantage of larger clubs. I can't speak on the motivations of other leagues to go ahead with it.

Using the Champions League as an example, whether you use 5 or 7, only really matters when you have vast quality differences between squads. When all your teams have quality in depth, it doesn't matter which you pick and any differences are negligible. At that point it is solely a preference decision.