QTE would ironically only work with popups. Enemy leaves melee without disengage. Popup. You have 3 seconds to comply, or something like that.

Otherwise, yeah. They'd have to severely slow down combat in order to give players time to respond. The camera does not jump instantly to who is moving, and even if it did, you wouldn't have time currently to figure out who is moving near who and so forth. It just wouldn't work.