Having libraries allow the community to explore rather than saddling it with a bad default. See the number of http server frameworks etc.
The real solution here is not for the stdlib to become a black hole, swallowing up every half-way popular library a but rather for “rustaceans” to adopt a more security-conscious approach to writing programs- C programs typically have few and well-chosen dependencies. Some languages, like Odin, completely eschew package managers because they see the very real issues stemming from writing a program with scores or hundreds of dependencies.