I haven't used HTMX but the author doesn't make a very convincing case. On the one hand they say,

> "But what about complex client-side state management?"

> You probably don't have complex client-side state. You have forms. You have lists. You have things that show up when you click other things. HTMX handles all of that.

On the other hand,

> I'm not a zealot. HTMX isn't for everything.

> Genuinely complex UI state (not "my form has validation" complex—actually complex)

But my interpretation is that any UI which displays the same data in just two places (like a "new notification" indicator as well as bolding new messages in an inbox, or a list of articles which can change dynamically as well as a count of the number of articles) is "complex" enough that you'll need client side state.