The issue I have is, if I understand correctly, you need to go to the server for everything. Their sauce is of course that server is close, maybe 10ms away. But it needs to be online, and so do you.

If most things interactive on your site need a round trip BEFORE the interactivity (e.g. a Like button) then this is OK.

However if you are writing a web app which does a lot of stuff offline and there is no reason for it to not work offline then this is an issue.

Where it is a bit sucky is something like clicking an expand button, and needing a network request for basically setting a {display:'block'} style on an element.

I might be strawman-ing a bit there because you would probably chuck in a tiny JS script to do that one job and not religiously follow "no JS".

But I am sure there are good examples of wanting offline capability.

However this is not a showstopper: This model is great for some things, bad for others. It is a welcome new choice in the palette of web dev options.

I imagine it might be premature optimization for many sites though, given that it is a trade off.

If you care about minimal JS to the client, another approach might be to use https://svelte.dev/. I have not tried it, but I am curious.