This is a fairly widely mocked opinion, it;'s the same caliber of criticism as the "we should improve society" meme. The fact that both sides participate in shared narrative isn't a sign that both are corrupt, it's a sign the narrative is important.

https://knowyourmeme.com/memes/we-should-improve-society-som...

To take a toy example, consider the George Washington cherry tree myth: https://www.mountvernon.org/library/digitalhistory/digital-e...

I was taught that as a kid as a straight-up truth as a package of patriotic narratives. If I had said, "Well that's a good story, but that never happened," the people teaching it wouldn't have said, "You're right! But it's a good story that has a nice moral." They would have been mad at me for contradicting patriotic truth. And madder still if I asked why they were feeding me false stories as if they were true.

In contrast, the people I've read who would point out the issues with the cherry tree story are generally more frank about why they're doing it and more honest about the limits of knowledge and narrative. Many are happy to appreciate myths as myths, for example, and to have nuanced discussions about the role of myth.