Catcher wear masks to protect them from foul tips/balls. Take it off when that danger has past.
Football players wear helmets to protect from being hit. Take off helmet when contact not to take place like on a fair catch or fly pattern if wide open in end zone.
Maybe this will help you:
Nobody but catchers wear helmets in baseball. Why? Foulballs/tips that no one else on the field can experience.
Every one on the football field wear helmits. Why? Countless reasons..
I wonder if the kid who played in front of me in high school had wished he had kept his mask on. Play at the plate he discarded the mask. Ball took a short hop and got him in the eye. Dropped like he'd been shot.from that day forward, we didn't take our masks off...
I can see taking the mask off for a pop fly but taking the mask off for a plate at the plate is crazy. Especially is there is a collision with the runner.