True, but other languages are not typically processed in the traditional mod_php way where urls are directly mapped to files in your static root, thus it's extremely rare to see e.g. python or ruby files served as static files.
I don't know what you mean. You just tell the web server what you want to do, and it will do it. Eg: "Process only files in this dir, and only accept requests to this kind of URL. And any request to that kind URL, pass it to this single php file".
Do software like XAMP have bad defaults and shouldn't be used for production out of the box? Maybe.
Has that helped a lot of people to get started, and make PHP the most popular server language for the web? Definitely.
Should we mock all php devs including experts, because of designers or ninja CEOs who tried/succeeded in editiing or making a website but made some mistakes in the process? The answer is still no.