partial or superficial knowledge or information leads to more serious errors than complete ignorance
A little learning is a dangerous thing, but a lot of ignorance is just as bad. Google
A little learning is a dangerous thing, but we must take that risk because a little is as much as our biggest heads can hold. Google
So they can only be talking about a superficial familiarity, not a deep understanding. As Alexander Pope said, a little learning is a dangerous thing. Google