Q2VKPT isn't using ray traced effects as you can find in some AAA games, SOTR, BFV, Exodus. It's path traced and doesn't use the old fake stuff. What does this NV's version exactly do...? Who the hell knows, is it a hybrid or a full on path tracing as Q2VKPT? Q2VKPT uses the original game data and it was lucky because Q2 includes information that wasn't used in original Q2 renderer but is present there anyway and can nowadays be used with more modern graphics methods. NV's version? Completely altered for sure since they added physically based materials and what not.
Bouncing rays isn't even that performance hungry, it's looking up the values from materials that is a performance hog. They show this in the Unreal video floating around here somewhere as well. Perfect reflections work fast but semi reflective materials, scattering, etc. is expensive as more things have to be calculated for a hit to a material.
The problem isn't what can graphics do, they are already doing it for decades but slower on CPU+GPU and farms in non-realtime for movies, single frame renders, etc. The problem is accelerating ray tracing enough so that we can use full path tracing and not be stuck with a hybrid renderer for another 2 decades where only very few effects get ray traced while all the rest is rasterized. Nice path tracing is super expensive, Q2VKPT runs by default the worst quality possible, 2 bounces I think and as a result many areas are pitch black as no rays bounce enough to get there.