I would go
with: "There's a lack of low hanging fruit at the edge of
the orchard. You need to head in a bit deeper to find it, but it is
still just as low."
I find that simply working on WP is the education one needs to realise what is missing.
"Good stubs" are still, well, good. They tend not to require special skills to
write.
Exactly. No special skills are required, you just have a look a little
harder than you used to to find something to do. A few years ago you
could click "random article", click a red link and write a stub. Now,
there aren't anywhere near as many easy red links.