Heh, I had the feeling this question would come
The arcade has long been and most importantly
consistently been the Far West when it comes to language and personal attacks. This led a great majority of the community to accepting that reality and to embracing it. If it were to be outruled, there would certainly be considerable anger in the community, and I believe a non-zero part of the playerbase would simply leave the game because of it.
On the other hand, FM has always had more regulations than arcade when it comes to that. More importantly, some years ago, the FM community completely changed and was made exclusively of new members who established a new, less toxic standard without even having a moderation team. The community then welcomed new and old members alike, and nearly all of them followed that new standard pretty happily. Unlike in the arcade, the majority would be angry if the aforementioned toxic behavior were tolerated. It's a matter of culture.
Plus, aside from all considerations of what the FM community considers as
fun, the FM community has the concern of bringing new people from other communities in; those communities happen to have standards that come really, really,
really much closer to the FM community's current standards than to the arcade community's.
This leads me to use the same argument about capitalism; it's just that the majority's culture is completely different.