I'm just anti unswerving faith in only it.
Nobody is suggesting using
only GPS. This is the problem with all these "GPS threads". It is only a matter of time before someone converts a GPS recommendation into a GPS-only recommendation.
You use the best tool as the main tool.
And you retain other methods for backups. If you have a VOR/DME then that's your next best backup. You can also call up ATC.
Dead reckoning is not a great backup because it works only if you have been operating it all along. That increases cockpit workload substantially, which some enjoy but most don't. Whereas a GPS can just be left sitting there, running, and you glance at it every once in a while.
I have just been reading about the Apollo programme. They retained autonomous navigation - ostensibly in case the Russians jammed the radio. So the space vehicles carried a very complex computer-controlled "star sextant" which was a servo driven telescope with position encoders on it. It was actually amazingly accurate and they could have landed on the moon with it. They continued to cross-check their position with this device throughout the programme, but the primary nav was .... guess what? GPS. It was a predecessor to GPS, using the same pseudo-random correlator technique, with base station(s) on the ground and a lot of computing power back home. The same methods are still used to position satellites in the correct orbits. So, in the mid-1960s, they knew where they were around the moon using "GPS" measurements from the earth, and it was those which were ultimately used. They used the best tool as their primary tool.