Its a cool idea in your head and on paper.
But it just wouldnt workout.

Proof of concept is the 3 grand companies. Back in the day, when you queued into Frontlines, your team is the GC you joined. It was heavily lopsided towards the Twin Adder.
More people were in the GC, the Best Players were in that GC, so the Immortal Flames and Maelstorm always get stomped.
So everyoned joined Twin Adder, till it got to a point it was IMPOSSIBLE to queue for frontlines.

Basically, one side would have an incredibly large advantage.
So now everyone is a free agent because of it