Devs wanted to store state in objects, so it became object-oriented. It also gained a really solid full-fledged web framework with a strong community, with Symfony; and some strong micro-frameworks like Laravel.
But it will always be interpreted and mono-threaded, and therefore never a good choice for high-scale solutions. Facebook has to invent a brand new language (Hack) and runtime (HHVM) that was close enough to PHP so they could spend millions spending their PHP codebase to it, in order to make it compiled and multi-threaded, and make it scale.