I love it, but it takes some time to get used to.
It is a new way to think compared to the "modern js framework" craze over the last 10 years.
But, you're right, it is the "old" way of using the browser/html with sprinkles of new interactivity.
Didn't even think about that.
Many times 3 lines of simple to understand htmx code will be equivalent 200 lines of VueJS code - and with a lot less bugs. It is insanely productive.
¯\_(ツ)_/¯
But, HTMX fits very well together with the traditional server-side rendered websites and probably you wont need to do much cognitive rewiring
https://hypermedia.systems
see if it makes sense or not
I like to sprinkle a little alpinejs in whenever I need some client-side things.
I love it, but it takes some time to get used to.