eeethey're not gonna add 6s lobbies unless you can play without weapon bans and class limits :\
Although this might not happen or work, maybe we should just allow no weapon bans and class limits and allow the 6v6 format.
Games will be played, and if the competitive TF2 as we know it with the 2 scout, 2 soldier, 1 demoman, 1 medic using certain weapons every time is so good, then let's show it to them. Pubbers may try the 6v6 format, go engineer/spy and etc. and realize it's not as viable as they keep losing each round and don't understand why. If enough of the competitive TF2 community plays the format we play, eventually they might learn what works and what doesn't.
Despite we are use to our class limits/weapon bans, and for certain reasons too of course, it might be good to make things unrestricted and let things go as they are in order for the game to evolve, like how CSGO gives the freedom of weapon choice, but certain guns are used anytime anyway cause they know what works. Same for Dota 2 to an extent. It wouldn't hurt to have it implemented, if we don't like it, we can just go back to our own matches/pugs/lobbies where there is weapon bans and class limits.