[chrysoprace]

I agree with you about timezones and I think a library like date-fns (and date-fns-tz) strike a nice balance by not using a bespoke intermediary object type.

As you say, some of them are built in and those should just be used instead in most cases. The problem is that when you leave the choice of library to use, then the choice isn't always obvious, especially for niche use cases. A library that's well-maintained today may not be so tomorrow when the maintainer falls ill, gets burnt out on work + open source work or simply gets bored of the project.

Deno has the right approach in this regard where they are creating standard libraries to go with their runtime which are expected to be maintained in the long term, but even then I'd still prefer built-in APIs in most cases.