Not only did PHP clean itself up a lot in the last few years, it also managed to do so while maintaining a great deal of backward compatibility.
It's not uncommon to pick up a really old library that used to work in PHP 4.4, stick it in a PHP 7.3 project -- maybe you need it to import legacy data -- and experience no issues whatsoever. You can probably also use the library in question in parallel with a modern dependency management system like composer, or any framework built on top of it, without any conflicts. This is Windows-level backward compatibility, and I mean it in a good way.
Why would anyone want that in this day and age? Because there are tons of legacy PHP code that still power a very large fraction of the web. Not everyone is writing new projects from scratch. Not everyone can afford a total rewrite. PHP's backward compability allows people to transition gradually at their own pace. It might not be sexy, but it gets the work done, and it just keeps working. That's all that matters for many, many businesses out there.
It's not uncommon to pick up a really old library that used to work in PHP 4.4, stick it in a PHP 7.3 project -- maybe you need it to import legacy data -- and experience no issues whatsoever. You can probably also use the library in question in parallel with a modern dependency management system like composer, or any framework built on top of it, without any conflicts. This is Windows-level backward compatibility, and I mean it in a good way.
Why would anyone want that in this day and age? Because there are tons of legacy PHP code that still power a very large fraction of the web. Not everyone is writing new projects from scratch. Not everyone can afford a total rewrite. PHP's backward compability allows people to transition gradually at their own pace. It might not be sexy, but it gets the work done, and it just keeps working. That's all that matters for many, many businesses out there.