... and is pretty much single-handedly keeping PHP alive!
If you're in the tech startup bubble it's easy to come to the conclusion that Python, Ruby and an assortment of minority interest languages with rabidly toxic fanbases rule the roost, but outside of that bubble PHP, C# and Java are quietly running the world.
If I want to create a quick script, I can just create a file directly on the server and see the result live, without having to compile anything or even restart the server. If I want to move it to a different server, I just copy-paste the contents of the file.