[ef4]

> having such features in the standard library makes a big difference for a newcomer.

And not just for the newcomer. The biggest benefit is that your dependencies and your dependencies dependencies can all compose better when they're all using the same standard implementation of feature X.

The extreme case of this problem was c++ in the bad old days when lots of organizations were writing their own String libraries. Inevitably, you'd add a dependency that pulled in yet another incompatible string implementation.