Yeah it's terrible in some use cases.

If only HTML provided a way to navigate <a> without adding a history entry, like <a nohistory href=...>.

If this was a real product i would market it as "Native time travel debugging! Go through your application state as you would go through your browser history!"

That would be terrible UX.

The real answer is that web developers should stop using anchor tags to target non-stateful links and should properly handle navigation to pages that are short lived.

But that battle is a bit like asking people to use their turn signals when merging.

Could you perhaps modify the iframe to clear the new URL from history using JavaScript?

You could also make it optional; perhaps there'd be syntax like <a href="asdf.html#myElement;no history">...</a> or something.

Probably would be better to make the no history default though.