Unpopular balancing opinion
Tl;dr: The game being balanced around competitive play is not a bad thing
Let me explain.
In professional league, champions when played by anyone that isn't TSM Zven are played to their fullest potential. That's why the changes made should be based off there. If a champion is overpowered when played correctly, for example Sejuani, but is extremely overwhelming when played badly, the thing that should be addressed is when played the way the champion is supposed to be played, and in this instance, nerfed, as she was a few patches ago, and the same can be said for any champion. If the game was balanced around iron-silver where the majority of the players are, we'd just get master yi and annie nerfs every patch. When was that ever going to be an ideal situation?
And then there's the fact that in low elo, players play for fun. In LCS, they do it as a job, and so do the high elo streamers. There's no reason why the game their career is based off should fuck them over. If I lose a league game, I'll just have a bad mood for a while and move on, knowing I don't have to keep playing. Streamers and pro players however, are forced to keep playing the game to make a living.
I always thought of this that way. If we look at basketball, and FIBA's rules, they make them according to the top level competitions. They won't randomly be like "Ah, that 12 year old on the play ground is too short, we should shorten the basket's height". That would make absolutely no sense.
I know most people disagree with this, but I never had a problem with it, generally speaking. Yeah we are going to have situations like the Riven one, but other than that, balancing around pro play or just high level play is the way to go.