Also, it’s not just that it’s boring, difficult, and undervalued, but also during development the code is constantly changing and to constantly spend 20 minutes updating documentation for a 3 minute change that might or might not solve an issue is horribly wasteful of time. So by the time a project releases, probably 80% of the documentation is outdated already.

The only exception to this I’m familiar with (though I’m sure there are others) is using OpenAPI to generate both source code and documentation from a configuration file. That way your documentation and code are always in sync. But that’s a relatively narrow use case that isn’t going to cover low-level stuff like algorithms.