If that was it, we'd all be writing Perl. Seriously. The documentation is better, the backwards compatibility is second to none, it's well designed (even if it's not what people expect, and people often misinterpret how it works because it's just similar enough to most procedural languages to seem the same). Particularly when compared to PHP (which copied a lot of parts of Perl, but did so poorly), it stands up well.

That said, I think you are half there. It's not just stability and documentation, but that with a minimum level of community, which PHP garnered by being dead easy to deploy back when that was actually a concern and in-language frameworks didn't abound. Perl lost a lot of community in the early 2000's, and never really recovered fully from that (relative to popularity of other languages at least).