I know everyone has a right to post what and where they want so long as they don't break the site rules. So from a "rights" perspective, I get it.
But what I don't understand is the driver behind it. Why waste time on something you're self-declaring not to care about? Is it because they feel morally superior and want to express that perceived superiority? Is it because they're worried the OP won't sleep that night without having seen their opinion that X thing the OP has posted about is shit/boring/pointless?
(Made-up) example: say someone started a thread asking "who do you think is going to win Sports Personality of the Year this year?" You can guarantee that amongst the posts of support for Mo/Laura/Andy/whoever, there'd be some where the poster felt the need to say "I don't give a tiny rat's ass" or "I never watch sport, it's all bollocks" etc.
It's fine to not watch or enjoy sport - but why then bother to open a thread with "sport" (or whatever) in the title and disparage it? Do they think they're going to convince the enthusiasts of the error of the ways with their devastating prose?
It would be like those of us who aren't parents for whatever reason replying to every thread about an aspect of parenting with "I haven't got children so I don't give a shit, OP." Yeah, thanks for that...that adds to the discussion how, exactly?
I feel like this about the facebook threads. someone posts a thread about it and the first 10 posts are guaranteed to be the high horse bridage saying things like "you shouldn't be on it", "it's shit" and "its your own fault to thinking that joining and engaging with a social media site that the vast majority of the population uses is a good idea".