it's the current circlejerk of complaints that is customary to Reddit/boards.
For example,
Morgana was complained on the boards for a while with outcry against her binding and base damage and black shield, but she never got any nerfs (if anything she got buffed from the mage support itemization which has been improving over the past season). Currently nobody complains about her even though she still does the same thing she's always been doing. And for the most part players consider her to be a balanced champion, she sees some competitive/non-competitive play, has distinctive strengths that make you want to pick her and is in a pretty healthy spot for the most part.
The issue is the "front page" of the boards, which is created from an upvote system (which for some moronic reason allows users to upvote things without even entering the thread or reading the content, meaning clickbait titles with thumbnails get auto upvoted by the masses), which leads to users believing that ideas supported by a minor group (such as those who have encountered toxicity) to believe that those ideas are actually the majority (which is untrue in the toxicity case, since the majority of players say nothing for the whole game).
For balance discussions, this is also the case, players with something to complain regarding a champion will whine and get upvoted by those who share similar issues. Even if they are a small minority they will get upvotes and will appear to be the majority even if they aren't.
And then there's the issue of the frontpage- you get upvote (rhymes with bores) who make posts to attempt to get upvotes so that they feel like they are getting attention (probably because they are lonely people). As an example, LaughingFish is popular poster for his memes and his hated by GD because they dislike seeing his memes taking up 75% of the frontpage which crowds out meaningful discussions about the game.