Given there are no infinite resources, one has to choose where to focus. Rust team seems to be focusing on the language and solving hard-to-deal-with but relevant problems - and on evolving the language, which is truly a remarkable feat when you are pushing the boundaries.

Libraries can be implemented by 3rd parties and maybe later adopted as standard libraries or become de-facto standards. That's how it has been done for most popular languages out there, and I think it's a smart decision.