These are the old high school weight room rules and does not apply any more. Sure, if you are a powerlifter you must touch the bar to your chest to make the lift in competition. Most of us working out in the gym are not powerlifters and have much different goals. Touching the bar to your chest can be very rough on the shoulders especially if you lack the range of motion. Many people can’t even use the bench press because it bothers their shoulders let alone bring it all the way to their end range of motion with heavy weight.
Even stopping to where your elbows are at 90 degrees is okay for those with shoulder issues. Most people are looking to improve their general fitness, strength, or size. Stopping short of the bar touching your chest will allow you to reach these goals without putting your shoulders at risk of injury.
Those who can benefit from bar to chest:
Athletes with adequate shoulder mobility. Some athlete may encounter situations where they need strength at their end range of motion. Doing THEIR full range of motion can be beneficial to their performance. If they have the shoulder mobility, then touching the bar to the chest can be done.
I was once at the gym and a guy nearby asked me to spot him on the bench. Not a problem, so I did. He did every rep bouncing the bar off his chest and then stood up grabbing his shoulder in pain. So I had to speak up. He said, “I think that only reason guys don’t go bar to chest is because they are pussies”. I told him that his shoulders would feel a lot better if he didn’t go so far down. Of course he was not to be reasoned with, so somewhere out there is a guy that has perpetual shoulder issues and a weak bench press. With just a small modification, he could have healthy shoulders and a much higher bench than the non-impressive weight he was lifting that day. I don’t care what weight and how he benches, but apparently he cared a lot and enough to wreak his shoulders over it.
But I like to touch the bar to my chest!: Ok, so you like the feel of the full range bench press or maybe it just makes you feel empowered, I understand. Do it as long as you don’t have shoulder problems or pain, but beware of the risk. You may also find that is ok to do the full range with light weight, but not so with heavier loads.