When I was growing up, I was often told "There is no such thing as a stupid question." The idea of this statement is that if you really want to learn, you should speak up and ask questions about what you don't understand. It is a simplification and there are stupid questions, so it is funny to read someone making fun of this cliche.
In the title statement, the speaker starts with agreeing with the premise and then by cleverly adding the ", but", the first statement is negated and the real meaning is revealed that the writer believes there are a lot of idiots out there.
As with many cliches, there is an almost as popular saying that is practically the complete opposite of this one:
"It is better to be thought a fool then to open your mouth and remove all doubt."
It is up to you to decide if you want to risk being thought a fool by not asking what may be perceived as a stupid question, or to go ahead with the question and remove all doubt about your being a fool, or ask the question and possibly learn something.
Asking questions is also a key part of the Socratic method of learning. I have been told that I naturally employ the Socratic method, without even knowing exactly what that means. I think people mean that I like to ask many questions. I'm sure there is more than one time that I've been considered an inquisitive idiot.
What other humorous sayings have you read lately?