And may His Noodly Appendages help you if you come across a function being used which has no documentation and a single decade-old comment from someone asking how it works...
And so, to plaster over it's many flaws, people start layering framework upon framework upon framework, each of which slows down the language significantly from all those shiny PHP performance benchmarks you see. And then they wonder why their shiny "what's an array? we need to transit 20 different chained method calls for that" is so slow...
And half of them are documented even more poorly than PHP itself. At least their code is in the same language you're already writing, though.