I agree that a moving map GPS when used properly
I think that is a contradiction. It is hard to not use a moving map "properly". You just need to look at it! The plane is in the middle, and the map is around it....
I am not sure how useful moving map is with full IFR flight. I am not sure how much heavy metal uses full moving map. FMS provides more than adequate "magenta line" nav, threshold to threshold, with terrain clearance being provided by planning, IFR, ATC and of course EGPWS. But that is not really relevant for virtually all private flying.
I see two problems in the above.
Firstly, the "old airliner" school of IFR flying, where you depart on an non-RNAV SID (a runway heading to X DME followed by some VOR intercept, etc) or a radar departure. The enroute is just waypoint to waypoint, with vectors in busy low level areas perhaps , then a radar arrival (again non-RNAV) and an ILS. 100% in CAS and 100% under ATC direction, with airspace classes being totally irrelevant. That is how airliners have been flying for decades. A moving map doesn't add a great deal to this, so long as you do it a couple of times a day
If you are less than good then you might get e.g.
this which would have never happened with a moving map. But it rarely happens nowadays because of high crew currency and - in the civilised world anyway - close ATC radar control. And EGPWS
The other is the "virtually all private flying" comment. About 30% of my TT (1k hrs) is IFR and about 10% of my TT is in actual IMC. That is pretty significant, and I don't fly the same route daily, and neither do the huge majority of private IFR pilots. We need all the situational awareness we can get.
We also often fly OCAS and a moving map is priceless because it shows you where you are relative to the CAS boundaries. Even in CAS (as is typically the case flying low level airways around Europe) the moving map is great because one can see a nice chunk of the route ahead, with waypoints, etc. A map is far better than a CDI showing the deviation from the track to the current waypoint which can be misinterpreted in umpteen ways.
With a decent moving map, either displaying the actual VFR chart (as with the Memory Map product for example) or supplemented by the VFR chart, makes it virtually impossible to bust airspace.
Those that do use a GPS but still do a bust have obviously still found a way to get it wrong, and it can be done (e.g. flying at FL054 under a FL055 base CAS on 1013 and then continuing to underneath another piece, this time base 5500ft, forgetting to reset the altimeter to the local QNH - nasty!) but there is very little excuse because the information is right there under your nose.