Typically that's because people try to use them on patches beyond a name patch. Even smaller rockers can be problematic. LC and smaller if wanting glue to be the only means of attaching to substrate.
Tackle twill fabric is usually good even with fairly dense patch patterns. I have never had a need to put stabilizer on (but I'm also not doing smaller swatches of it either, I can see backing being used to help with hooping smaller swatches of it, especially if these are already pre done patch blanks, need to have something at that point). Tackle is already a "harsh" substrate as it is, not like it's moister wickering as a patch.