People don't do it because it is counter productive. Respected people have their supporters. Unless you first bury your argument in adequately respectful terms it will get downvoted. Regardless of content.

You cannot say "The Linus rant about C++ is just wrong". You need to first blather on about why Linus is a great guy but has his limited perspective and from that perspective he is correct. However there is a world outside of that perspective where he is wrong.

If I posted the Linus rant on C++ I'd just be called an idiot. Nobody would worry about my perspective because, to my knowledge, I don't have any supporters to appease.

It is just politics. It affects tech communities as much as anywhere else. People get invested in their side. If you challenge their side then you must be sneaky about it.