Honestly, I used to agree with this but then I started to realize that, no matter how many nerfs/buffs they put out, there will always be a Champion who is more OP. By nerfing a Champion, another Champion will indirectly be buffed, due to the nerfed Champion not being as strong against the latter anymore. By 'gutting' a Champion, another (or maybe a couple) Champion[s] will indirectly be buffed, due to the latter not being strong at all or simply being way too weak to contend with the latter.
You are then inevitably stuck with only two forms of action: either (A) you learn 1 or 2 of the current 'OP' Champions, or (B) you get really, really good with your 'sub-par/not-so-OP' Champion[s] to the point where the 'OP Champions' don't make a difference.
Personally, I choose Option B, because I can't play most, if not any, of the current 'OP' Champions.
I don't play Jungle at all, so Vi, Lee Sin, and Hecarim are no-go's for me. I don't play Top Lane too often, so Darius and Poppy are no-go's. Mid Lane is fun for me but I can't (for the life of me) learn Yasuo, Zed, Fizz, LB, Katarina, nor Syndra. (I seriously suck with Assassins, as you can see.) ADC is do-able, but I can't play Draven, Twitch or Vayne, so my options there are limited. And Support (my favorite role), I don't understand Janna (mechanically), nor can I effectively play Braum, Zyra and Karma.
This leaves me stuck with the only thing I know how to do effectively: Make due with the 'sub-par' Champions that I can play. Once you gets this locked in your head, it makes the game, not only easier, but fun again. (At least, it did for me.) Hope this helps relieve you of your 'stress?' or whatever it is you are currently experiencing. If not, well then, at least you have this little tidbit here. :3
[slayer-jinx-wink]