Game integrity is game integrity, regardless of the level of damage done by a certain “playstyle”. If a single player was intended to have the power of several characters, then characters would not have been originally designed as they were. Personally I do not see it being “lumped in” with botting, unless you were using said multi-character keycloning. One press of a button should NEVER have been accepted in regard to causing multiple characters to act simultaneously as one.
Alt tabbing? Have at it.
“Actual cheaters”? Seriously, dude?