Your 'nasty' may be another person's "challenge" depending on whether you side with those being challenged or not. I have seen mod messages claiming"nastiness" which to me have been little more than taking the p*ss out of posters making fairly nasty/inappropriate comments. And there is little point reporting them as they remain on view; then when their views are challenged those posts are removed. You get what you create.
Do you think that you are alone in feeling this way, that you are somehow individually persecuted.
It works both ways.
Firstly, what you describe above is not always true, or at least is only true for you, from your personal.perspective.
Many posters do not take the time to read posts before replying with either aggressive or worse, passive aggressive responses which invariably have a trolling effect.
Other posters never actually state an opinion...which is infuriating but prefer hide their thoughts while they pick out single words and try to derail the comment ,or worse, to appear smart. Rather than actually being smart, which many members, even those who's posts I don't personally enjoy, clearly are.
Neither of the above activities add anything to discussion and only serve to make SC&P the unattractive silo of preening self esteem that it has become.
You get more opinion in cafe, because cafe has a wider audience, which is why some leak their discussions towards that board for debate and I suspect why others seek to claw these debates back into the silo of comfortable status quo.