You’ll get a lot of different opinions here, what works for me is big thick tires and big thick tubes.
This is such a load of crap, we rarely ran DH tubes on my brothers bike at races and nor did many other people. Ever so often we’d put a heavier tube on the rear but not often and not a full-on DH tube!
Pro racers tend to run thin lubes and small brakes too. Racing != spending a week or so doing multiple runs per day. For most amateur riders, especially if they don’t have a lot of experience riding in the Alps, the goal isn’t ultimate speed, it’s keeping your bike working. I’d hazard that most of us are usually trying to slow down rather than looking for that extra few tenths of a second 🙂