When I did my solo XC in 2000/2001 (?) I was not supposed to use any radio nav.
I actually knew VOR/DME stuff (it's hardly rocket science) but it was wiser to not tell anybody...
The total ban on non-visual nav is pretty recent. The skills test in 2001 included just a VOR/VOR position fix.
You got to remember that the bulk of the PPL community is very static. Look around at your local airfield. The average age of the regulars is probably 60+. So most regulars are flying on stuff taught 20-30 years ago.