Why does node.js recommend not to use its built-in assert module?

In its API reference website, node.js recommends not to use its built-in assert module and use "userland" libraries instead.

Contrarily to what is stated here, I don't find they are limited at all, as far as my use case is concerned.

As I'm planning to go full TDD in that use case, the first point makes me ask this: what might go ugly with node.js assert module?