Not necessarily. It depends on what you need. For example suppose you were implementing an news reader with two panes. Left pane is a list of titles and preview

Not necessarily. It depends on what you need. For example suppose you were implementing an news reader with two panes. Left pane is a list of titles and previews, right pane is a full article for the selected item in the left pane. You can make the left pane a list of links to dedicated pages, and then add an htmx attribute to indicate that when the user has JavaScript to instead fetch a html snippet with just full article and swap it into the right pane. If you had a reasonably bounded set of articles you could statically generate all the /article/id.html and the /article/id/snippet.html files, though a backend probably makes sense.