To "get" HTMX, you have to think server-first. State is persisted on the server and all state-change logic is performed on the server (often triggered by http requests from a "dumb" client).

If you hang on to "possible states of the UI" that are client-side only then yes you'll have some difficulty implementing server-generated HTMX responses but more importantly, when your client has state that sometimes isn't in sync with, or shared with, or validated by your server, you're setting yourself up for errors and bugs that will exist regardless of framework.

In short, HTMX forces you to apply "single source of truth" concepts to your application.