It's already been explained here a bit but I'll elaborate further:
Friendlying (aka being 'peaceful'/refusing to attack the enemy team) is against the rules.
You can freely friendly on trade and idle, but if you do it outside of those servers you will be banned if caught. Friendlying may be fun for you, but for most others it ruins their fun seeing a dead weight teammate throwing sandviches to enemies, not helping his team, and taking up a slot from someone who actually wants to play on the server. This is why we ban for friendlying.
But you can friendly without consequences on trade and idle where you're not ruining everyone's game by doing so.
Skial isn't going to add areas to non trade/idle servers where people can go and friendly. That defeats the entire point of why we ban friendlies