> Now obviously one might wonder why HN works this way. The reason is that the HN codebase came about as a way of field testing Arc [Graham's 100 year language].
This is really the key point: continuations are the wrong way to write this kind of application. It's significantly more work and there's no benefit from doing so but it allowed someone to test a pet idea and, having done so, fixing it would mean admitting that doing something because it's cool isn't good engineering.
The kind of application is specifically Hacker News, not a generic website or webserver. See the essay linked here for what kind of application this is:
Continuations are a questionable fit for web applications in general, however. HTTP is stateless and it requires a lot of extra work to build an abstraction which pretends otherwise. I prefer to embrace that from the beginning so the entire design matches the nature of the medium.
This is really the key point: continuations are the wrong way to write this kind of application. It's significantly more work and there's no benefit from doing so but it allowed someone to test a pet idea and, having done so, fixing it would mean admitting that doing something because it's cool isn't good engineering.