To your last point: If you're making an HTMX app, you're probably using built-in browser inputs instead of custom JS-based ones like react-select. If you NEED react-select, you probably should just use react. But if your site is mostly just displaying data with html and updating that data with forms, htmx will work great with much less complexity and effort.

I've only toyed around with htmx, but it really is refreshing. Of course you can't do everything that you can do with a fully-fledged client side framework. But once you try it out, you realize that more of the web is just markup + forms than you realized. I wouldn't build a live chat app with htmx, but I would totally build a reporting dashboard.