Isn't that still the case?
At least here in Europe the word Backend Developer is basically synonymous with PHP Developer.
Every other language for backend development is pretty niche. Sure there is Java (and C#) for the enterprise but that was already there back then. Ruby had a good run but modern PHP with frameworks like Laravel could reclaim most productivity benefits so not that fierce of a competition. JS with node, sure but I mostly hear it in the context of micro services which is the opposite of wanting to get something done.
> PHP barely ages - from 1999 or 2010 or 2020, it looks similar and works fine.
Yes but no. PHP takes stability and backwards compatibility quite seriously but the language and culture around it has changed tremendously. The wild west days are long gone, it has gotten much more professional and mature while adding many modern language features.