Champion diversity, has the problem really ever been balance?

**TL;DR: Pros got better over time, balance did not get worse. **

Of course low diversity in higher elos has been balance on a number of occasions. Mordekaiser bot lane, bruiser Fiora top, and mid season 6 Ashe/Jhin are all some good examples. Technically it still is balance now since any champion that goes ever so slightly above the power levels of the others could possibly become a highly contested pick. So yes, call it clickbait if you want, it's still about balance. Since balance determines high elo picks and pickrate is so low, only around 20 champions out of over 130 getting picked, balance must be really shitty, right? If balance decides champion diversity and champion diveristy is low, balance must be pretty bad with riot being terrible at said balancing.
I disagree with this statement(for the most part). While Riot has been biased as hell, released absolute fuck ups of champions, fails at reworking, certainlyT, and made huge mistakes(hey you know those things that can be really hard to balance around? Let's release it all on one championinsert camille), sometimes people don't recognize something very important.

Champion Diversity now is frequently compared to champion diversity in the past. You can't compare these two things though. A statement like "Season 6 had only 25 champions frequently picked in LCS, with 15 niche/off meta picks, while Season 3 had all the champions frequently picked aside a few" (made up numbers but you get what I mean) while it could be true, doesn't hold much weight in comparing old LoL balance to new LoL balance. Why can't they be compared though? It's pretty simple, as a game becomes more popular and the pros more skilled, you have to play the absolute best picks. It's easily described as what I like to call, pro player power creep. As time passes, pro players try to be better than the others then others copy them to make sure that they can stay pro and keep climbing. This isn't an issue, it's just how things work. It's the natural progression of everything. It's easily seen in real life sports. The 100m dash times decrease over time, the swimming times decrease, etc.

How does this apply to league of legends though? Over time pro players get better, so over the course of seasons, a challenger player in season 3 might be more like a low challenger or even diamond player if they do not improve over that time span.

How does this apply to balance? I can finally use some league examples now. As everyone knows, anything can work in bronze if you are good enough. Ap Urgot? Go ahead. Onhit AD Aurelion sol? Sure, but I want some of the stuff that you are smoking. Of course this doesn't hold true as you get higher and higher up the ELO ladder eventually reaching challenger and LCS where you need to play the best performing champion possible in order to even have a chance at winning.

Diversity goes down as you go up the ELO ladder because in low skill games, the difference between Xin Zhao and Camille won't matter as much. As you get higher and higher up the ELO ladder eventually the subtle difference start to shine through and eventually they cannot be ignored. The margin of error decreases and small differences between champions become massive issues.

You could theoretically fix this, you could, in theory, make every champion balanced to a competitive level and make them all have equal amounts of power. This would take loads of work(as in years of work doing nothing but balancing) and could be a massive time waste if a new strategy is discovered that invalidates everything you set up. All this being said releasing more overloaded champions like Camille is definitely not a good idea.