The only part that htmx adds is avoiding reloading the hypermedia and allow swaps via AJAX as you say. But the programming model stays hypermedia-based. For ex

The only part that htmx adds is avoiding reloading the hypermedia and allow swaps via AJAX as you say. But the programming model stays hypermedia-based. For example, your server returns markup, not Json to a React frontend or similar. This simplifies things a lot though it also has some disadvantages. Advantages: if your backend changes the return to extend functionality, the hypermedia will be returned with no required changes on the frontend. On the other hand, if you want to do a data-based json API htmx is not what you want, because it conflates returning functionality (embedded in the hypermedia) with presentation, instead of returning only data.