It's obvious why he didn't write the game in x86 assembly. It's also obvious why he didn't burn the game to CD-ROM and ship it to toy stores in big box format. Instead he developed it for the web, saving money and shortening the iteration time. The same question could be asked about next.js and especially about taking the time to develop Bun rather than just scrapping next.js for his game and going about his day. It's excellent for him that he did go this route of course, but in my opinion it was a strange path towards building this product.
I also wonder how many people who sing the praises of an HTML file with a script tag hosted by Nginx or whatever have ever built a significant website that way. There’s a lot of frustrating things about the modern JS landscape, but I promise you the end results were not better nor was it easier back before bundlers and React.