The opposite is also true; a good package manager can avoid the stdlib to bitrot ala Python, because you can easily swap out an old module by simply repackaging as a third party dependency.
On the contrary, the benefits of having a standard set of batteries, especially those upon which other might be developed, is fundamental to a sane ecosystem development. For instance, a standard framework for async I/O programming is important, because then people can write thousands of protocols that can be fully interoperable; if 2-3 different framework arises, each one can then develop its own ecosystem of protocols and libraries (not interoperable), and it's hard to think that each one would be as rich as the one in the former scenario. The same can be said for a HTTP library, a threading library, a XML/JSON marshaling library, a threading/concurrency library, and so on.
On the contrary, the benefits of having a standard set of batteries, especially those upon which other might be developed, is fundamental to a sane ecosystem development. For instance, a standard framework for async I/O programming is important, because then people can write thousands of protocols that can be fully interoperable; if 2-3 different framework arises, each one can then develop its own ecosystem of protocols and libraries (not interoperable), and it's hard to think that each one would be as rich as the one in the former scenario. The same can be said for a HTTP library, a threading library, a XML/JSON marshaling library, a threading/concurrency library, and so on.