I think it is easier to start scripting in PHP than it is in Perl. If you are a complete n00b, you don't know where to find this "Perl interpreter" that you have to put on the first line after a cryptic "#!". If your provider has set up PHP for you, you can rename a .html file to .php and you have your first working php script (well... in a sense that is).

Also, in PHP if i want to create in image, i can do that out-of-the-box. No modules to find, download, make, make test, make install, import. It just works. I remember when i wanted to work with images in Perl i was totally intimidated by the amount of choice i had. Not to mention that i had never heard of "make".

So what everybody already knows about PHP (its easy of use) is a forte. It is also probably why so many people use PHP.