AMD can do RT fine as long as the game is designed with RT only i.e. metro EE, if attached on top along with raster methods then sacrifices have to be made for amd as we have seen with their sponsored titles e.g.
- shadows cast from only certain light sources and/or only on certain assets/objects
- reflections only on certain bodies of water or/and surfaces as well as much lower resolution
Same story for AO and GI.
When they haven't done the above then performance can crash hard and it's probably down to not having "dedicated" hardware for RT workloads like nvidia and intel, in fact, I think someone did some testing and found that when rasterisation/other graphic settings were reduced, performance was better whilst keeping RT maxed.
As for nvidia always making a problem and giving a reason for people to upgrade, you mean innovation?
physx - I wasn't a fan of and imo was largely a gimmick where effects were locked out and removed from the game to put it behind a paywall i.e. locked to nvidia but again, not a good tactic at all, some of the effects were very nice like in batman though e.g. volumetric smoke/fog and reacting to your movements etc.
gsync - had it not been for nvidia, we would have been waiting 2 years for adaptive sync (amds branding name for that is freesync) or maybe even longer, not to mention, gsync when released was superior in many ways compared to the first freesync displays i.e. no issues with black screens, flickering, poor FPS range, lack of low frame compensation, lack of variable overdrive (which is still the main advantage of gsync for LCD based displays). Tftcentral have done a good education piece as to the advantages and disadvantages:
A detailed look at variable refresh rates (VRR) including NVIDIA G-sync, AMD FreeSync and all the various versions and certifications that exist
tftcentral.co.uk
And once again, ray tracing is NOT a nvidia thing......