there is a big difference in the cost of static hosting and CDN (think Cloudfront / S3) for static stuff and running an active piece of hardware for static stuff that doesn't change. Like orders of magnitude. Sure for small sites it's not that much but it's still orders of magnitude.
also the answer to a large number of my interview questions ends up being figuring out how you can just effeciently serve the stuff from a CDN/Blob Storage. You can scale the crap out of this for quite cheap.