[wvenable]

I disagree. Especially if those non-std libraries are built on other non-std libraries and so on. Trusting a single organization is much easier than trusting a chain of organizations.

[nicoburns]

If they are officially maintained, then by definition they are written and maintained by the same organisation as the std library.

The difference is, having an external library allows it to be versioned with breaking changes if necessary, without breaking consumers.