Online they seem to be, probably down to alot miscommunication & anonymity.
Irl for me personally though respectful discussions are quite normal to encounter.
I think it is because you have relationship levels with people you know irl. Someone that is just a casual acquaintance that you just have small talk with you will be very civil and hide a lot of your ideas/thoughts etc.
Where is with a close friend or family member irl you might say stuff you would not to casual acquaintances.
Where as online because it removes the human factor we just say stuff that we would never tell a stranger to a bunch of random strangers etc.