> the vast majority of (non-native) react applications require a back-end, at the very least to deliver them to users

I mean, I guess if you consider me opening an index.html file in my browser requiring a backend in that my desktop operating system is the "backend server", then yes, but that's not what I was referring to. I don't think most folks would consider a CDN to serve static assets to mean "your React app requires a backend" in the traditional sense -- but that's a game of semantics.

> htmx-powered applications can be local-only via service workers

Do you have any examples of an HTMX app running completely client-side using service workers? Funny enough, the only example I found online ends up using Preact to render templates in the SW, but as a whole, this looks less ergonomic than simply using <insert JS library here> to build a SPA: https://joshi.monster/posts/serverless-htmx/

> there is a large overlap in practical applications that might be built with either, so it is good to know the strengths and weaknesses of both for comparison.

I could agree with this. I only care that people understand there are tradeoffs.