A lot of good programmers today started their web experiences with PHP. Now probably they are using the latest cool thing, but it served as the "BASIC" of our times, and is still active and trying to fix its issues.
Also, and this is not a PHP merit, but a disaster with other dynamic languages such as Ruby, the performance you get by default with a simple PHP application, is good enough that is almost always the DB to blame, not the front-end, when there are issues under load.