I'm guessing they, like most websites, try to cater to the most common type of visitor of their website. Most of which has JavaScript enabled, even though I'm sure the percentage of visitors with JS enabled is much much lower than on other websites.
Right, but what they actually did strikes me as a slightly weird halfway measure for supporting the NoJS use case. Optimizing away the NoJS page does not gain any significant amount of speed for the average-case visitor, but it does communicate to the NoJS user that while they're at least a citizen (an improvement over most of the web to be sure!) they're still a second-class citizen.
Again, this is much better than nothing. I'm just pointing out that this design pattern isn't as good as it could be, and if someone reading this wants to implement full support for the NoJS users they can do so by just making the NoJS landing page be the default and replacing it with the interactive app's content root.
