Today, when one can have workflows via jekyll/git/Continuous deployment, at what frequency of "often-changing" should one move away from static websites to a php based solution?
Or a simple guestbook or hit counter.
Where the lines may blur is JS front end talking to a BaaS... This may make it possible to glue up impressive sites using just HTML and JS with no custom backend requirement.
PHP is still widely used, but there's a myriad of other contenders: Java, ASP.NET, Python (Django,Flask,etc), Ruby (Rails), Perl, Javascript (Node,etc) and others.
I'm not sure about PHP being the "king". PHP might be the most widely deployed thanks to either FB or the huge number of legacy bulletin boards and wordpress sites, but in terms of new deployments does it still dominate? Probably not. (For novices, a static site generator is definitely the way to go, until you run into it's limitations.)
I also made a start with PHP. Still, PHP has been slow to learn from other languages and frustratingly refused to change established behaviour. I found PHP to be far more "dangerous" for the amateur programmer than other languages. Finally, I switched and never looked back.
From teaching beginners, I actually think Python + Flask has a similarly shallow learning curve, but more room to grow and to "do it correctly" (e.g. the templating is much cleaner and the routing much more powerful). I recommend it.
Hopefully you get the point.
(I do agree that PHP without something like Symfony, Yii, ... Laravel, even Cake could be very dangerous, or at least, counter-productive for amateurs trying to learn though)
To expand on this, static website generators are best for generating documentation and small blogs. It falls apart when you have a large often-changing content. This is where PHP is still king of the web.