In such ecosystems, for long-term, evolving production work (when you don't know all your eventual needs upfront), you need to have the institutional capability to build from scratch whatever components you might need. Just in case whatever you need later doesn't yet exist in the ecosystem.

Then you need to retain the personnel who give you that capability. Because they are rare, in a field in which 99%+ of developers only glue together NPM or PyPI packages. (And many use Web search or, now, Claude Code to do the glue part.)

If I founded a startup doing mostly Web-like server backend work, I'd consider doing it in Racket or another Scheme, and then using that as a carrot to be able to hire some of the most capable programmers. (And not having to bother with resume spamming noise from hardly any of the 99%+ developers, who will be pounding the most popular resume tech stack keywords instead, because their primary/sole goal is employability.)