Player feedback is useless and shouldn't be used.

If Riot made all their balance changes based on the things we players say in Boards and on Reddit, this game would be 20 times less balanced and as such be so much worse.

Human input just isn't a good source of this kind of data. We, all of us, every single player that ever exists, are inherently biased and subject to personal experiences that don't match consistent reality. We have a personal struggle and blame the thing we are struggling against instead of ourselves. We credit ourselves for our success instead of the thing we used. We only remember the extreme cases. We don't notice things that go in our favor but notice them easily when they go against us. Our minds naturally avoid the notion of other's being better than us.

We can win 30 matches against a character but the only match we remember is the 31st where they wrecked us, and now we think the character is op. We could suffer a bug that does something major, say making some auto attacks count as 2, and never notice when we play as the bugged person. That bug could only occur every 10th attack but when we are against the bugged person we are convinced it happens every 3rd. You could truly be certain that an overpowered champion you play as is perfectly balanced, so that your wins are because of you. You could truly be certain that a balanced champion you play as is underpowered, so that your losses aren't because of you or the enemy being better. You could truly be certain that a balanced champion you play against is overpowered, so that your losses still aren't because of you or better enemies. On top of all that, the entire community could agree about something, and all be wrong.

These are basic errors of human psychology. They effect every single person, and they effect every single aspect of our lives. In fact, being less effected by these errors is one of the main symptoms of clinical depression. Not making these mistakes is literally bad for you, from a health standpoint. That's why we evolved to make them.

The the words of players are wholly unreliable, to the point that they simply can't be used for balance decisions. Riot has to heavily prioritize objective data that doesn't relate to anything anyone says. Even if almost everyone is saying something, that doesn't make it true. For it to be true, the data that doesn't come from us has to say it.