I would bet against this hypothesis.

Perl exploded because it was the easiest, richest ecosystem available to plug into CGI and the web.

PHP & Ruby & Python then collectively covered the same waterfront whether you wanted “easy” or “fun” or “simple”.

And I would propose that PHP attracting the developer cohort who wanted “easy” and Ruby/Rails attracting the developer cohort who wanted “fun” were each individually more damaging to the Perl ecosystem than Python.