[bhouston]

It is also a limitation that many initial DOS 3D software rasterized games had (e.g. Descent.)

This is because perspective transform requires a divide per pixel and it was too costly on the CPUs of the time, so they skipped it to get acceptable performance.

[BearOso]

It's also commonly known that Quake only did a perspective divide every 16 pixels.

It's funny that, in today's CPUs, floating point divide is so much faster than integer divide.