Internet forums are not kind to minority opinions. If you express a minority opinion, you can expect a dozen or more people chiming in with the majority viewpoint, along with the general sentiment that you’re an idiot for having the minority opinion. So an internet forum tends often to reduce to a text version of the scene in Airplane! where everyone is lining up to take their shot, against the OP, and figuratively high-fiving each other in the process. The same thing can be seen with stupid or awkwardly phrased questions or comments. Plus there’s the communication barriers and personal space issues already mentioned, and you can be rude without worrying about being smacked upside the head for it.
I knoow wat u k
I think its this. Not so much the possibility of physical violence IRL, but that IRL its pretty rare to meet and talk with a bunch of completely random strangers that are in no way consequential to the rest of your life. Most of the people I talk to are family, or friends, or friends of friends, or people I work with, or neighbors, etc.
Obviously I still fight with those people sometimes, but there’s a stronger incentive to keep things civil when someone’s connected to you in some fashion and alienating them might cause trouble down the line.