That said, FastCGI and similar technologies were inevitable and something like PHP-FPM isn't much more difficult to actually run in practice.
Still, having a clearly defined request lifecycle in wonderful, especially when compared to something how Java application servers like Tomcat/Glassfish used to work with Servlets - things there have gotten better and easier too, but still...
There is an HTTP server handling all the HTTP stuff and process launching (API gateway in AWS parlance), and the communication between it and the “script” just uses language or OS primitives instead of more complex APIs.
The 2000s were quite wild in how things changed… suddenly you have giant frameworks that also parse HTTP, a reverse proxy. At some point even PHP became all about frameworks.
I wonder if we wouldn’t have a more open, standardized and mature version of CGI/Serverless if it had been a more gradual transition rather than a couple of very abrupt paradigm shifts.