No one who loved themselves wrote Xlib apps directly either.

I actually wrote some stuff directly because I was young, poor and stupid.

First year in uni my windows laptop broke, had to lug around a heavy second hand underpowered ppc powerbook and wrote some application I needed that I didn't want "bloated".

Font handling, shared memory backbuffers, network api, etc.. as I wrote in another comment. It is an API to solve over the wire graphics in the late 80s/early 90s era using idioms of that time, and already by year 2000 the problems (rasterization power) didn't exist nor is it even a suitable API surface (even less so 25 years later).

Athena widgets were great! /s