One of the things I have noticed in languages is that after some iterative evolution the piled on features and syntaxis sugar make them look bizarre and hard to read. Probably the weight of backwards compatibility and that the initial paradigms have picked up the easy to understand real estate. And there are no good ways of getting out of the corner you have coded yourself in.
Probably because compile/interpret is one way street. There is no way to lets say view/transform a part of the code in functional or imperative depending on what you need to do with it.
Reading modern php or even worse mixed generations code base feels like another full time job on top of the regular one - coding with it.