[simonw]

I think "skill issue" is often deployed (including here) as a shortcut for what you said - "the only thing stopping them is that no one has helped them understand".

(I try not to say "skill issue" myself because it comes across as rude.)

[saghm]

Yes, but with the context that the person saying it is almost always the one who does understand, and is choosing to be snarky instead of helpful.