"Doom mapping is often called simple because it's just like drawing a map on a piece of paper. Quake mapping, on the other hand, is a lot like building with Lego."
Thread on an interesting new (still in development) way of building Doom maps: https://www.doomworld.com/forum/topic/103999-announcing-bsp2doom-build-doom-levels-with-a-quake-editor
Thread on an interesting new (still in development) way of building Doom maps: https://www.doomworld.com/forum/topic/103999-announcing-bsp2doom-build-doom-levels-with-a-quake-editor