Because PHP (heavily inspired by Perl, but not as well thought out) came with all the glue to directly use it to generate web pages. Then came Ruby (also inspired by Perl, but with a more mainstream syntax, and nicer in some ways), and Ruby on Rails conquered that space even more. Also, Python came along which is indeed a bit more suitable for larger projects needing structure.
Meanwhile, Perl was being badmouthed by people who couldn't handle its flexibility and thought it was unreadable and unmaintainable. But that wasn't the main issue, after all PHP was worse in those two respects, yet it flourished.
Meanwhile, Perl was being badmouthed by people who couldn't handle its flexibility and thought it was unreadable and unmaintainable. But that wasn't the main issue, after all PHP was worse in those two respects, yet it flourished.