He didn't assume that. He's simply saying that at the PGA Tour level, when averaging as little as 3' difference in your proximity to the hole shifts you 100 places on the ranking… that details matter and getting the right wind, the right yardage, etc. take a little more time than a guy who thinks he hits his 7-iron 155 but who usually hits it 140 the few times he actually hits it solid.
Now, they can certainly speed up… and do some of those calculations while the others in the group are playing among other things, but… @klineka wasn't arguing that they be granted five minutes, either. We had a fit over JB Holmes taking 4:30, after all, on the last hole of a tournament, to lay up.
I don't think you're going to win that one. They shouldn't care as much, no, absolutely not. It'd be ridiculous to care as much as they should/do.
The flaw here is to assume that their shots are better the longer they take to play them. I'm not suggesting for a moment that they simply step up and hit it but they don't need in excess of 5 minutes for each shot.
The second assumption is that amateurs shouldn't care as much about their shots. I don't feed my family with mine but for all the effort and expense golf requires, my shots are kind of important too.