Earlier quoted context omitted.
I am an experienced programmer but I've only touched PHP a few times, years ago. What are the best books or tutorials to get an overview of modern PHP?
I think the question is why should you bother with PHP at all? It had its time in the history of the web but that time has passed, long, long ago.
Because some people just prefer it. They know its warts and have learned to work around it. For me it is a much easier prototyping tool. The crazy number of built in functions and libraries out there makes it so. Eg: Want to turn on and off an IoT device at sunrise and sunset? Well for other languages you have to go find some library or depend on an external service but no not for PHP. For PHP there is freaking built in date_sunrise and date_sunset functions! [1]