Yes, this is actually an industry wide problem with no easy solution unless the community itself is honest about who they are actively cooperating with in-game - with Discord and like, it is so easy to pretend everyone is independent, and there is always one bad apple group that will use such things and smash a server for a win, because that is apparently just so much fun.
I agree. That said, with the older titles there's "precedent" so to speak for larger and more organised teams. I would argue that the solution is commander mode in these instances.
Commander mode permits several separate squads to be coordinated towards a common goal. Of course, squads wouldn't always follow the commanders orders - but I can attest to many BF4 matches coordinating efforts and getting results with completely random squads.
I've created a seperate post asking for a "squad leader voip channel" to fill that command and control void that we have now. During the beta, trying to prevent zerging by typing in team chat almost always resulted in people having a sook in what is supposed to be a "team and objective oriented" series.
"Hey lads, we should split up and flank xyz, instead of funneling into xyz?!" would often get responses of "shut up" etc.
On some occasions, I did manage to drum up some action through team chat - but it's not the same.
