Also, trying new technologies was literally a goal of the project.
WordPress is insanely customisable - it's "just php". And sure, maybe his new skill learning could be coding on WordPress :-)
Ok, so learn php when they could just use js which they likely already know and likely get paid to know.
Wordpress and php are negative value skills, you do not want to advertise that you know those things as a developer because someone might try to hire you for them.
This was unnecessary.
I'm already in the part of my career where learning another programming language is not what will take me to the next level so unless there is something unique about a programming language that makes it very useful I'm not interested in learning it.
Learning how to use more tools is not necessarily better when you are already proficient in other more flexible tools.
There's billions of dollars in revenue generated yearly from PHP sites. And not just "legacy" either, I'm talking evergreen PHP apps being built and generating revenue.
It's just as alive and well if not even more alive than some other languages people prefer over it.
Tooling changing in JavaScript is unique to JavaScript only because of the language constraints. PHP, Ruby, etc are all controlled by the developer, whereas JavaScript is controlled by the browser vendors and end users of those browsers. You have more things to work around, inconsistencies to smooth over, and more importantly larger ambition on the frontend than most things can currently support, so new paradigms and frameworks come out to tackle that.
Also 5 years in internet time is a long time. So I'd probably not say it "changes so fast"