If you're not sending just exactly the necessary HTML to replace the target's HTML; if you need to parse JSON, then even jQuery would be better suited.
The whole idea of HTMX is to get rid of the extra steps.
I guess I could see it for decoupling your need to control the API you're using. The case where you have an existing API, whether your own or someone else's, and just want to get a new frontend hooked up to it.