Why Duo

"Finding an excuse to use a smurf account is a piece of cake. Just say I do not use sub accounts to stay down in low ranks. 'I switched to controller/MnK,' or 'It’s my solo account'—the players on the receiving end of this ruined matchmaking couldn't care less about those reasons."

Truest thing I've read on these forums in a long time. Secondaries are a cancer on the game. Respawn could put an end to them tomorrow, but will always allow them on all the pretexts you listed (and I'm sure quite a few more) completely ignoring the indisputable fact that they are a violation of the terms of service they themselves created.

Proving only that in gaming, as in life, rules are made only for those who are dumb enough to follow them. Great message to be sending to people, Respawn.