Some people were teenagers when that was the best you could get, so I'm guessing they see it as a "good old days" baseline that they can be principled about while indulging their nostalgia.
First off, I want to say you can totally have a design ethos that covers game engines as much as irrigation systems -- Lee Felsenstein explicitly cited Ivan Illich's notion of 'convivial technology' as an influence on his modems. And Illich mostly talked about bicycles.
What I see in this project is a specific kind of appropriate technology -- 'toaster compatibility' -- mixed with conscious adoption of old methods and aesthetics to serve and signal that end. Which is cool, IMO.
HTMX uses similar techniques in trying to 'bring back' hypermedia and reduce dependencies, although I think they're after a different kind of simplicity. And of course, their Hypermedia Systems book makes similar nods to 90s-software aesthetics: https://hypermedia.systems/
Still, for a simple game limiting to 800x600 for performance and dev reasons - why not? But for me it means I see no use case for myself.