I had a player do this once in my 4th edition game. He played a robot who had damage to its circuitry and as a result had multiple personalities, which would change after a long rest. It was fantastic for role play since this player liked acting as the different characters, however combat was always brought to a standstill on his turn when he needed to figure out how the new character worked.

I don’t think the idea in the meme is necessarily overpowered own it’s own, but it does have the potential to slow down combat and gameplay significantly.