This is great to see. Quake and Doom were all about elaborate fake 3d and elaborate fake raytracing to run fast and look amazing on slow hardware. As technology improved, first we got a real 3d engine and now we finally have a real raytracing engine.
A nitpick: DooM (1 and 2), just as well as Duke Nukem 3D were indeed "2.5D" elaborate fakery of 3D. One of examples of the ruse: a level was basically a (floor, ceiling) height map, and there could be no two overlapping rooms one above the other.
On the other hand, Quake (1) was an early pioneer [1] of real, actual 3D, including an OpenGL backend and all that. That's one of the reasons it required significantly beefier hardware: needing a Pentium for smooth gameplay, while DooM would run perfectly fine on a mid-end 486, which is a generation older.
[1] cf. Marathon