You can do anything with plain JS too, but that doesn't mean you'd want to. The problem with Hotwire is that you do often have the server round trip in there. That's fine most of the time, it just gets a little harder to understand as the complexity rises. That's not to knock it, I think Hotwire is pretty good.
In what scenario would complexity be higher in a simple UI - server loop? Doesn’t complexity usually arise from having additional logic in the browser and maintaining state separately?
I guess it depends somewhat on how you imagine up something and write it. I was working on some drag and drop UI that had multiple sortable lists and an action area. Figuring the server side and UI at the same time didn't work out. I reversed and implemented the UI with its required state, and then it was easy to transform that state to what the server side required, and vice versa.
Complexity is tricky. Are three simple things more complex than one thing thats harder to understand?