you need a server for HTML to work, as practical matter. But yes. There IS a workaround to that too, if you're REALLY determined, but you have to format your HTML a giant JS comment block (lol really :))
[edit: I'm sure there are still some file:// workflows for docs - and yes this doesn't address that]
You don't need a server for HTML to work, I can just hand you a USB stick/floppy disk/MO disk for your NeXT with HTML files on it.