Probably. To be clear, what's being stated here is that Doom, Wolfenstein, etc. don't actually render from 3D internal data structures like Quake and later firs

Probably. To be clear, what's being stated here is that Doom, Wolfenstein, etc. don't actually render from 3D internal data structures like Quake and later first-person shooters did. The level layout is inherently 2D and some tricks are used to render the environment in a way which looks like a 3D perspective. But it is fundamentally a sort of flat-lander's pseudo-3D.