Half of the entire internet is Meta properties.

That’s the other half.

Coincidentally also PHP.

Facebook started out PHP; but they ship-of-theseus'ed it into Hack by replacing the standard library, the language, and the runtime engine, so now it's a totally different thing with only a few superficial similarities (FWIW IMO Hack is much better than PHP, I'm sad that it never gained traction...)

Much of what was good in Hack just got rolled into PHP.

And if it's not cpanel, it's Plesk