OK, how about this:

chisels *look* a bit like screwdrivers, or paint scrapers, or pry
bars, or flower garden digging tools... and sometimes get used for
those things, especially by beginners. so in beginner level tutorials,
it makes a lot of sense to *specify* that a chisel needs to be sharp,
where it's not so necessary to specify that jointer blades need to be
sharp.


nah, that couldn't be it.....