> Just because is requires "special" zip software on the server?

Yes. A web browser can't just read a .zip file as a web page. (Even if a web browser decided to try to download, and decompress, and open a GUI file browser, you still just get a list of files to click.) Therefore, far from satisfying the trilemma, it just doesn't work.

And if you fix that, you still generally have a choice between either no longer being single-file or efficiency. (You can just serve a split-up HTML from a single ZIP file with some server-side software, which gets you efficiency, but now it's no longer single-file; and vice-versa. Because if it's a ZIP, how does it stop downloading and only download the parts you need?)