This doesn't seem to be the same thing. The article isn't about being unable to type before JavaScript starts executing. If I understand correctly, you're unable to type until a network request to Cloudflare returns. The question is: why not allow typing during that network request? JavaScript is running and it's observing the keystrokes. Everyone understands that you can't use a React application until JavaScript is running. They're asking why the network request doesn't happen in the background with the user optimistically allowed to type while waiting for it to return.

(Separately, I don't think the article has adequately demonstrated this claim. They just make the claim in the title. The actual article only shows that some network request is made, and that the request happens after the React app is loaded, but not that they prevent input until it returns. Maybe it's obvious from using it, but they didn't demonstrate it.)