PHP's worst feature is programmers who only learn PHP. Even worse when they become the most vocal members of the community.

This creates an echo-chamber-like environment that's not favorable to the evolution of a rich programming language. Since they never got to learn other languages (at least not enough) its evolution is guided by partial impressions of what other languages offer. It then becomes a collage of partial implementation of concepts similar to what other languages are based on.

Try explaining recursion to someone who only knows 8-bit BASIC (where all variables are global and functions are implemented as subroutines with known input and output variables). It won't work.