Not having to spawn a new process greatly decreases the time it takes to process a request, which greatly increases the amount of requests you can serve with a given amount of hardware.
These days everything that would've been CGI is now FastCGI (even PHP). Or in other words, run one server whose only job is to reverse-proxy requests to another server over a slightly different protocol.
It can be used in shared scenarios, but it's nowhere near as automatic as "every file with a particular extension" like PHP...
I would hope that this would cause more people to realize that allowing total control of the things you use to be centralized in one person (or business) is bad, but well... quite similar things have happened to plenty of other open source projects before.
So they throw Cloudflare in front of it and get defaced yearly. I've worked for companies (thankfully not in a position dealing with the website) that did just that. Somehow they're even still around a decade later. To be fair though that was actually Bluehost, not a VPS.