That doesn't stop you from making a doom clone with simple pseudo 3d. But yea, for the average user, making a game in 3d in Construct is more trouble than it's worth. Search for a game called "Mega Thumb:Dream Match" by Quazi and I, It shows you the extent of 3d in Construct Classic. If C2 ever gets mesh distortion (which I doubt it will, since the sprites aren't polygons to begin with) then a 3d game like that will be theoretically possible. For now though, you can still make simple 3d with sprites alone, and a fair bit of math.