" I can't speak for anybody else but when I get a visual I turn straight towards a 5 mile final. Why would anyone do otherwise?"
Well, they do. I for one always gave a visual when asked for to number one, but then I had to hold off on turning number two to base until I'd seen number one turning in. The fact that a visual approach isn't predictable actually makes it harder to get a consistent gap behind him.
What methinks you haven't considered (among many other things beyond your ken) is that tower may have a reason for not wanting approach to allow a visual.
It's been rammed into me on this side of the pond not to give a visual if there's any kind of sequence happening unless you've got the aircraft to a point where the visual will ape an instrument approach.
In all seriousness brain fade, and getting away from the acrimony for a moment, you haven't got the big picture in the cockpit, even with TCAS. Besides that, ATC usually don't make the rules but we do have to follow them.