I shouldn't have to hide my dislike for an idea! We need to communicate to win, and communication doesn't just boil down to "Oh kiss up to them" because, if it did, then we wouldn't have phrases like "Bad idea" and words like "No." and "Don't."
I don't even really see how it's a negative attitude, either, especially not when you're trying to win and improve your chances of winning. There are definitely good ways and bad ways to disagree, and plenty can verge on toxic, I won't deny.
Edit: This may be an awful comparison, but the W. Churches thought the same way; You can't show dissent or question anything they do. It's honestly a bit tyrannical and counterproductive.
Edit2: In the example, Akali was using her KDA to slag off my team. So, I just decided to "Hey, dude, you suck as much as me. You're 5/6/0. Shut up and quit BMing the team." and she actually did just that with some pushback from some other people.
Sometimes kindly rephrasing "Don't be a hypocrite" gets you somewhere, and those sometimes are worth the times it doesn't - because those people who listen likely won't be toxic again, whereas, as you said, the toxic people would continue to be toxic anyway.