The folks who designed and wrote Perl should be congratulated for their work. They have designed a forward-thinking language that is totally extendable.
The capability to extend a language is not only a practicality but a must. Of course, no one language can include everything that is needed. To be sure, Perl does a fine job at doing almost anything a programmer needs, but when it comes to needing something it does not support, you can extend it rather easily.
You must consider several pitfalls when creating extensions, but with a bit of thought, none of them are insurmountable. Judging from the wide range of extensions available, it seems that this indeed is the case.