Market share of WordPress as website platform in 2011 : 13%
In 2020 : 38%
Yeah, php is not growing. Growing might start to become difficult when you en 40% of the web.
Sure, websites like TechCrunch, BBC, Playstation Blog or Variety use it but they have done so for a long time. Newer websites/companies are not using Wordpress and maybe not even PHP. Medium runs on combination of Node and Go, Twitch has gone with Ruby on Rails among others, Trello runs on MongoDB and CoffeeScript on the frontend and I could go on.