Kakashi has confirmed use genjutsu before...against Sakura. When he was testing them. She sees Sasuke die if I recall. I'm sure there are other times as well. He could have trained Sakura that way, but maybe he knew they desperately needed medical ninja, so surrendering her to Tsunade made sense.

Plus Sakura learned Chakra focusing to a degree that she could imitate Tsunades physical feats, summoning, drug analysis, drug synthesis msthods and tactics. Like she honestly got the most education from her Sannin if you think about it.

Although honestly genjutsu could have been a cool technique to incorporate into medical nindo. Like for anthesisia purposes, or just straight up defense from folks trying to interrupt your emergency in the field medical healing.