That's the "secret" of PHP. It's 20 years later and it just works. Many other front-end development tools and frameworks have come and gone in that timeframe yet PHP persists. Why? Well, I'm not a PHP expert but it sounds like they care about backwards compatibility. You don't have to continually reimplement everything all the time, which both costs money and discourages further investment. There are reasons COBOL is still around 50+ years later.