People will be offensive in the real world but I don't think we should encourage or accept that kind of behavior. If we build a society where people are shamed and shunned and not allowed to participate (whether it's a short timeout or a longer ban) when they behave poorly then hopefully we can reduce this kind of behavior in the world and instead of accepting it, people will be more comfortable fighting back in a positive way instead of simply flinging insults back which was how many of my childhood bullies behaved.

Playfighting is a different topic and typically even when you play fight, you set certain boundaries and there are things that you don't say/do. Good friends will recognize those boundaries and not cross them. You wouldn't call your friends soft and say they lack mental resilience for having boundaries, would you?