Comment by CraigJPerry

I guess it doesn't have to use JavaScript for the back behavior. It could use a server-side rendered referrer if that hasn't been stripped by the browser?

You say that JavaScript and fallbacks for menus is a solved issue but the number of menus that are just an absolute clusterfuck is ridiculous on the web today. They're really not a solved issue, Progressive enhancement is hard to do. Genuinely hard in some cases.

On balance, while this is not without flaws, it's interesting. Accessibility, deep linking, reduction in cognitive load for the developer. There's some merit here.