I could but I’d rather not. With a controller in one hand and a mouse in the other there aren’t many buttons near my fingers, I’d have to let go of one to do some stuff anyway for some functions. Plus it makes UI glyphs flash between keyboard and controller which is irritating.
In medieval times, when you had the flu, the prescription was lots of water. Not to flush your system and keep you hydrated as is modern wisdom, but to balance your humors, which is made-up nonsense.