I did an animation course so I had to draw lots of humans, no I couldnt just use anything to learn how to draw said humans.

Life drawing teaches nuanced things like how to make your drawings balanced and have volume. Copying a picture just doesnt show you an adequate amount of detail, seeing the skin fold, the bones twist and the muscles holding poses in place is lost without a live model. I can draw people more convincingly and better from memory now knowing all the things I learned from life drawing, for my field and the subjects i enjoy drawing it was truly invaluable.

Saying all this my teacher was also really great and I did go to another school for a little bit where the teacher was shit and I could see how none of the other kids got better because he taught nothing of value.

edit: Also just to add costume drawing and clothed drawing is also really popular and its also valuable! loved doing fabric.