Well, in all honesty, I've stopped using PHP at v5, when it was all running as CGI scripts. So I'm not sure I'm doing it justice since I'm pretty outdated on its development.

I've never seen PHP being used for those usages. So I probably made an assumption here that it isn't, or rarely is.

All the languages I listed generally run their own server, and can handle the full request, down to its connection. While I remember PHP only managing the payloads from an existing server, running as an embedded script which the server delegated too on the last step for final rendering of the response.

So for example, it couldn't manage any type of long running in-memory process or anything like that. And it didn't have direct access to IO, as that's all managed by the containing server. Things like that, which not all REST APIs would need, but is generally something I'd expect to be able to do for more generic backend work. Don't know if there are now ways to do all this.