I would think in most cases someone using Phoenix would use LiveView for these sorts of dynamic updates instead of htmx.

a lot of elixir devs dont even believe in liveview so that's a harder sell than a phoenix backend with some more popular framework on the frontend

I think HTMX makes alot of sense for content that is a bit static but still needs some update and interactivity. Im building a job site right now and using htmx for job postlistings, search etc. And liveview for logged in view of creating and managing job posts.