Using ‘blind’ to mean ‘ignorant’ is like using any disability label as a synonym for ‘bad’—it turns a real condition into an insult.
Why is "ignorant" a synonym for "bad" (as a moral judgement, like "bad person")?
It just means you don't know something, which is usually a relatively bad situation for you, but it doesn't make you a bad person.
If you think otherwise, that's on you.
"Flying blind" is a completely standard idiom originating from flying while blinded by e.g. cloud or darkness. Its meaning is a figurative transplant of a literal description.