You should be able to use the query part of the URL (after ?). You can get at it with Javascript, but it doesn't influence which static HTML page is served.

They absolutely can generate the file tree so that each slide has its own url.

They also could use the query part on the url rather than anchor.

Lastly statically hosted doesn't mean no URL rewriting, they could again catch links to parts easily.

The poor UX of these tools is just a lack of will, not a technical limitation.

Then again hacker news should probably not blanket delete the hash in URLs either.