To be honest: that was quite possibly the greatest part of learning PHP for me!

PHP was the first language I learned; the fact that I could deploy it to nearly any shared host [of which there were a lot of freebies] allowed me to rapidly program and debug; which I find was crucial to my initial learning.

Hindsight being 20/20: of course I agree with you, now.

But I'm still not convinced that young me would've been able to use the built in server. I certainly couldn't be bothered to setup Apache (et al) and a working PHP interpreter.

Rails is a bit different, since you learn about the built in webserver when going through their "hello, world" tutorial. If excellent tutorials surface for PHP, then perhaps I can see the "FTP-to-test" pattern being obsoleted.

To me: PHP's greatest asset was that A) I didn't have to setup my own development environment, and B) there were so many [free] development environments already setup!

I'd learn to love setting up servers, but that came far later [in my chronology anyways].

tl;dr: FTP and common PHP setups actually removed a large barrier to entry for a young programmer. I think the "FTP-to-test" anti-pattern was probably one of the more useful ones in my toolkit when it came to my initial learning.

Wait, running the built-in server is one command (and no configuration), and it's quite reasonably claimed that Rails' equivalent built-in command is helping the adoption of Rails by people who are now in the position where you previously were.

It seems to me like it should be at least as easy to fire up the built-in web server as to learn FTP and sign up for some random shared hosting account, right? That is to say, isn't this even a lower barrier to entry than the FTP approach?

I doubt it. People that do this kind of shit won't have the DB installed locally.

PDO and sqlite take care of that nicely.

People that can't be bothered to have a dev server running hardly will be bothered to use PDO and specific settings for development and production.