I don't know what to tell you. It's a blog post. Simple apps are how you start to learn things. Nobody is saying that doing this is the most amazing end all be-all JS is dead and over lololol.

Some people like Rust. Some people like web apps. Some people want to use Rust to write web apps. If you don't, there are tons of other technologies you can (and should!) use to do that, and someone saying "hey if you're interested, here's how with a small example" isn't a threat to any of that.