"a zero day is an unknown backdoor" this shows both that they are trying to explain things to absolute noobs, and that they themselves dont know what they are talking about, a zero dayvis just a vulnerability which was not know to the people maintaining system. A backdoor is quite something else.
Also fuzzers also found 'zero day backdoors' and they didnt end the world.
Why have automated Lysenkoism, and improved on it, anybody can now pick their own crank idea to do a Lysenko with. It is like Uber for science.