That's a problem right there. Maybe that made sense to the Greeks, but it definitely doesn't make any sense in the 21st century. "Knowing" falsehoods is something we broadly acknowledge that we all do.
Furthermore, OP’s choice of putting “know” in quotes seems to suggest that author is not using the word as conventionally understood (though, of course, orthography is not an infallible guide to intent.)
IMHO, Gettier cases are useful only on that they raise the issue of what constitutes an acceptable justification for a belief to become knowledge.
Gettier clauses are specifically constructed to be about true beliefs, and so do not challenge the idea that facts are true. Instead, one option to resolve the paradox is to drop the justification requirement altogether, but that opens the question of what, if anything, we can know we know. At this point, I feel that I am just following Hume’s footsteps…
To know something in this sense seems to require several things: firstly, that the relevant proposition is true, which is independent of one's state of mind (not everyone agrees, but that is another issue...) Secondly, it seems to require that one knows what the relevant proposition is, which is a state of mind. Thirdly, having a belief that it is true, which is also a state of mind.
If we left it at that, there's no clear way to find out which propositions are true, at least for those that are not clearly true a priori (and even then, 'clearly' is problematic except in trivial cases, but that is yet another issue...) Having a justification for our belief gives us confidence that what we believe to be true actually is (though it rarely gives us certainty.)
But what, then, is justification? If we take the truth of the proposition alone as its justification, we get stuck in an epistemic loop. I think you are right if you are suggesting that good justifications are often in the form of causal arguments, but by taking that position, we are casting justification as being something like knowledge: having a belief that an argument about causes (or anything else, for that matter) is sound, rather than a belief that a proposition states a fact - but having a justified belief in an argument involves knowing that its premises are correct...
It is beginning to look like tortoises all the way down (as in Lewis Carroll's "What the Tortoise Said to Achilles".)
https://en.wikipedia.org/wiki/What_the_Tortoise_Said_to_Achi...