This is my first time hearing about it, despite daily driving MacBooks for 10 years. Does it have any advantages over other compression software? I've been using Keka for a long time and it has yet to disappoint me.
Then in 2001 OSX came out, with a new executable file format of “a specially named and structured directory in a boring UNIX file system”, and Stuffit’s reason for existing began to vanish. I’m honestly very surprised someone is still updating it now.
Mac OS X 10.3 (Panther) introduced native .zip support, and that seems to have largely taken over these days. I wonder how much of that is due to it being easier for CI systems to produce .zip archives rather than DMGs.
Unlike many people, I think the resource fork was a good idea. It structured files in a consistent way, and they were easy to examine if you had the right tools. The shortcoming is that there was not standard way (or maybe too many standard ways) to transfer files between systems intact. There was too much risk of important data being lost because the system you were transferring the data to (or a system you were transferring data through, or the software you were using was configured to ignore the resource fork) didn't recognize the resource fork or its encoding.
(It is also worth noting that a lot of file formats tend use something similar to resource forks these days. Resource forks are a bit like using zip files as a wrapper in, say, ODT and ePub files.)