GPS etc are all good but are not totally reliable, nothing wrong with map clock compass.
Now try that in France among its mass of restricted/prohibited military airspace, and countless other places where people get exceedingly nervous if they see a blip on the radar in the wrong place.
Your method of navigation isn't even appropriate to the UK and it's mass of low level airspace.
The only thing one can say for it is that within the 45hr PPL it is all there is time to teach, given the junk planes people have to rent they can't rely on anything in the instrument panel to survive the flight (even if it works to start with) and absolutely nobody in flight training wants a more expensive PPL on their price list. They already see a constant year on year drop in students.
You may be an exception and if so that's great, but I usually find that the anti-GPS people do most of their "flying" over a beer or three, and if they have done any significant distance ever it was decades back when the world was a different place.
Today, you need to be 100% sure of your position, and there is no OBE to be had if one c0cks it up.
Radio navigation also just happens to produce a much lower cockpit workload, which makes flying a lot more fun and the pilot is far less likely to join the vast majority of new PPLs that chuck flying in permanently in the first year or two - many of them doing so because they realise (correctly) that the skills they have been taught are really quite inadequate for going anywhere for real. Not that the average school gives a damn; their motivation is taking money off people.