And possibly easier aiming/coordination/stability with the camera and hands at not just eye-level, but also nearly right up against the eye, moving in unison with one’s head. Just a guess though. Sports television cameramen seem to do just find tracking the ball without using a viewfinder.
When you hold up a camera to your eye and use the viewfinder - it’s a third point of contact. You’re also using your face to stabilize it.
Trust me - they’d get rid of the damn viewfinder if it wasn’t often requested so much. Using the viewfinder is just a lot easier than the back of the screen in many situations. (Especially outdoors. Think about rain or whatever else going on getting on the screen)