I assume he refers to npm/pip/cargo to be the multiple os option, not saying the last one is obviously better for multiple os. At least that has to be because that's the only option that is os independent.

Of course it sucks because the essentially uncurated dependency trees result in either instability on updates, or missing updates. Of course also the natural OS updater won't help you out with pip/cargo/npm, but it will help with apt, yum, snap, and flatpak.

I was talking about the other ones, but since you mention it, yeah, many people use Bash on Windows, from Git Bash which is part of Git on Windows, which pretty much any developer forced to use Windows will install in order to use Git.
Developers often prefer to have less interfaces to maintain when possible.