For me the issue isn't that it's something for you and your team, it's that it's too easy to get. It's not super easy, but it's definitely not hard so I don't feel like it says I'm awesome when I see it, it's like a secret acknowledgement that you don't suck at the champ as bad as you could ha.
As for having a ranked ladder for champ skill I guess that could be cool, but it would be kinda boring. You wouldn't have the ranking metrics per game like you get now, and honestly it would just be champ win percentage on over 15-20 games or something modified by MMR. Like a challenger player w/ a 50% win rate over 30 games on a champ is obviously better than a bronze player with 100% win rate over 30 games (although if you can always win w/ a champ why are you still in bronze lol) because the quality of opponents is higher. However maybe a Diamond player with an 80% win rate is better than a master player with a 53% win rate on the same champ, and is just not as good at other champs? So it would petty much be like ladder, except then win percentage with in the tier on a particular champ would be used to rank I suppose, and maybe if you had a really high or low (like x>70, x<30) win rate on the champ over enough games to tell it would drop or raise you over the people one rank above you. Still seems like it would be boring since it would be so similar to regular ladder unless you're like 90% wins on one champ and lose all your games on other roles/champs.
