Is Zuckerberg even any good at PHP?

No

https://gist.github.com/nikcub/3833406

Was PHP any good back then?

PHP, surprisingly, has legs. I started using it at my job in circa 2000, then moved to Rails, then to Node, then back to PHP for another project. It had lots of problems in 2000. But it has been fixed over the years.

It's not the dinosaur people make it out to be. The main concern was the number of threads it creates, and how that limits its scalability. But modern *Nix cores can handle more than 1024 processes. Node definitely improves efficiency by using async architecture which reduces OS load, but PHP isn't the devil as some claim.

I think there's a treadmill habit of JS frameworks that make anything >2 years old seem out-of-date, but PHP has it's benefits... assuming one adheres to separation of concerns (something that was casually disregarded by the same pedants when they discovered React, Angular, and Vue).

Wow, that was a soapbox rant.

I understand how much PHP improved, hence I tried to imply past.