In-game is moderated a little more stricter, and for the most part the severity of loss is much higher.

If you're banned on forum, I don't think the ban extends to in-game. If you're banned on forums, then you're banned on forums alone. Whereas with in-game you have the potential to lose hundreds or thousands of cumulative effort.

If bans on forums extended to in-game bans, then a lot of what happens here would quieten down.

Plus, the purpose of a forum is to debate and discuss more than anything else, so you get a lot of conflicting personalities, and generally speaking people can take disagreements as an attack, regardless of what side. Compared to in-game where you're more just using it as a social outlet, so the interactions are more of a social manner.