You might also be thinking about creator codes, which are stored in the resource fork. There was a small flare up among Apple bloggers almost ten years ago around how those were being ignored in Snow Leopard;
http://livecode.byu.edu/helps/file-creatorcodes.php . Took me awhile to remember this one.
It's a shame that small quality-of-life change got more negative press than the more unfortunate dumbing down of AppleTalk and dropping of HFS write support, also in Snow Leopard.
I was going to link to Cult of Mac here but the web ad density of that site has only gotten worse, somehow, and
the editorial that first brought this up on TidBITS is kind of a meandering mess in the comments.
Anyway, my apologies for the derail. My entire workflow for managing old Macs would be harder without resource fork support in Mojave. I was surprised by the stronger claims made in this thread that seemed contrary to what I can do. ;-)
