This is one of the things I like the most about the fediverse in general. People who only wants negative engagement are hard to come by and easy to avoid.
And even if lemmy/kbin grows so much that that kind of users start to migrate from reddit to any of those platforms, it's posible to block the users or even defederate their instances, because if they keep that attitude it will reach the point that only instances that are already massively defederated for their behaviour will accept them, or they will be forced to form their own instances, that will promptly get defederated.
In centralised social media, this kind of people and behaviour are almost imposible to avoid because their algorithms are designed to promote that kind of engagement.