The bench press can kill you. It’s the one lift where the barbell is directly above your throat and the vital organs in your upper body, and there’s pretty much no way to bail out if you fail the lift.
Because the bench press can potentially kill you, you want to take extra precautions to ensure your safety during the lift. One of those precautions is using a spotter.
The problem with using a spotter on the bench press is that pretty much everyone does it wrong. Amateur and well-meaning spotters are so focused on making sure the barbell doesn’t kill the lifter, that they get in the way of the lifter performing the lift correctly. The typical gym-bro bench spotter will distractingly hover over the lifter’s head and place their hands close to the bar so that they’re ready to assist the moment they see the lifter seem to struggle. Worse, they’ll touch the bar while the lifter is struggling to push it upwards. That just messes up the bar path, and in assuming some of the effort of the exercise, deprives the lifter of the benefit of completing what could have been a successful, albeit grindy lift.
You’re spotting well on the bench press if you’re mostly out of sight. You should only touch the barbell to assist the lifter if you see the barbell going down (when it should be going up) or if the lifter asks for help.
Even when using a spotter, I’d recommend taking some of the same precautions that you would when safely bench pressing without a spotter. Specifically, NOT putting collars on the barbell. If for some reason you as the spotter aren’t able to help the lifter get the barbell back up into the J-hooks, you’ll be able to help him tip the barbell to one side or the other to let the weights slide off.