This reads like a rant of a person caught too much in their own bubble, a bubble in which hash maps seem to be of extreme importance. I've coded a lot of C in the past few years, and I can count the number of times when I would have actually needed a proper high performance hash map with all bells and whistles on one hand. A piece of code where hash map lookups are so frequent that it becomes a performance bottleneck is either badly designed, or a special case which needs a very careful implementation.

Builtin hash maps are convenient for "dictionary languages" like Python or Javascript, but beyond that they are highly specialized and tailored to specific data sets and hardware properties.