I suspect the problem is that every feature makes it possible for an entire class of algorithms to be implement much more efficiently and/or clearly with a small extension to the language.

Many people encounter these algorithms after many other people have written large libraries and codebases. It’s much easier to slightly extend the language than start over or (if possible) implement the algorithm in an ugly way that uses existing features. But enough extensions (and glue to handle when they overlap) and even a language which was initially designed to be simple, is no longer.

e.g., Go used to be much simpler. But in particular, lack of generics kept coming up as a pain point in many projects. Now Go has generics, but arguably isn’t simple anymore.