I like HTMX, I use it on my blog. But I will say, in the niche where I need some dynamic DOM changes without needing a full-blown SPA, raw JavaScript with some basic utilities like jQuery is not so bad.
The issue with htmx is that it is fairly prescriptive of how one should go about building dynamic interactions, and it becomes complex quickly if the dynamic interaction is more than trivial. I don't disagree with its philosophy at all (as I say, I use it for my own site) but it becomes an issue when my product owner tells me that I need to do some funny dynamic thing because it will make the business or clients happy (for some reason), and then it becomes a mission to wrangle it with htmx attributes. And I have to follow that, because as much as it pains me to say it, making stuff pretty and dynamic on the UI is an easy way to score points. It is one of those areas of enterprise software development which seems like a huge upgrade to non-technical people whilst not requiring too much effort.
The one thing raw JavaScript is quite well suited for is hacking together some DOM manipulation. I dislike JavaScript in every other domain except this - its in this arena where its leniency is very useful.
> it becomes an issue when my product owner tells me that I need to do some funny dynamic thing
Okay, but on the other hand maybe you should do the right thing and say no.
I agree that one should push back, but I suspect we have different notions of when to do that (which is fine, my approach here is not fixed in stone). Making a page needlessly dynamic would be a concern for me if it violates business rules or for whatever reason harms the overall system. But if it doesn't do that, and it genuinely does make the business and users happy, then I'm happy to do it and then get a bit of leverage to take some time to tackle tech debt that needs addressing on the backend.
> it genuinely does make the...users happy
But you have no idea if it does that, you just have the word of the PO who's not actually building anything, they're at best just copying what others are doing (ie being derivative) or at worst just doing guesswork.
How about offering an alternative: a UI/UX that takes the web as it is, a primarily document-based format with navigation and data entry? A lot of cool stuff can be built on top of that.