It's not extra work. The site in question was for making a reservation. A basic HTML for would have satisfied that requirement and worked completely without javascript. Any additional features could have been built with javascript and the site would be no different to users on modern browsers as the current build, but it would still work on the author's mom's browser.
Progressive enhancement isn't about building sites completely without JS. It's about building resilient sites that work on edge cases like this.
Progressive enhancement isn't about building sites completely without JS. It's about building resilient sites that work on edge cases like this.