[ars]

> I am a huge fan of code modularization

These days that's no problem. But back then computers were slower and memory much tighter. Making clean interfaces to integrate things made the code too slow and large.

On the other hand, projects were smaller, so there was less need.

[astrobe_]

Or maybe not. The modern version of segment tuning is cache friendliness. Also, with modern virtual memory, function layout may be important in order to minimize page faults.