A little knowledge ...
... may be a dangerous thing*
The key thing, as per the Dunning-Kruger effect, is that what makes "a little knowledge" dangerous is a lack of realisation (usually, but not always exclusively, on the part of the holder) of its exiguity. If one really knows how little it is (i.e. one is aware both of a wider context and one's own relative ignorance) a small amount of knowledge can be quite useful --- not to mention being an unavoidable step on the path to greater knowledge!
Who wouldn't rather support a user with some knowledge rather than none? It's only once they think they know more than they do that you really start to have a problem. I certainly encourage all the family and friends I support to learn as much as they can about their systems before they call me (even if it's just writing down error messages rather than saying "it's broken").
* Yes, I know it's not the original quotation. I was once humiliated in a meeting when I said I had only a little knowledge of the area but I thought I might have an idea, to be rebuffed by someone saying "Well, as Francis Bacon said: 'a little knowledge is a dangerous thing'" --- you know the sort of guy I'm talking about. What I would like to have said is "Well, I think you mean Alexander Pope, and I think he was talking about a little learning rather than knowledge, but I think you've both made your point and proved it". What I actually managed to do was to stammer out my idea whilst blushing like a halfwit. It was wrong, but the two people whose opinion I really respected told me it was a good idea, so that was some recompense.
"A little Learning is a dang'rous Thing;
Drink deep, or taste not the Pierian Spring:
There shallow Draughts intoxicate the Brain,
And drinking largely sobers us again."
--- An Essay on Criticism, Alexander Pope