Uhm, for the same reason we have rules out in real life. So everything doesn't go to hell.
If there were no rules, this forum, no, this site, would look very similar to what you would get if you took a hammer and smacked your own foot with it hard for a few hours: There would be a lot of pain involved, it would not look like it would ever be fixed again, and it couldn't possibly have been looking like that due to intelligence.
So either it's taking the smart way following the rules, conforming a bit to the social etiquette you get affected by when you are online, or it's leaving the internet or going somewhere where you are not around other people.