I think people find it insincere because pointing out that both parties in question have a problem doesn't change anything about the situation or the problems.
It is most often used as an attempt at a defense by calling out other guilty parties. Yes, we should like to live in a world where anyone calling out a problem or injustice only does so from a place of unimpeachable moral authority. But we do not live in such a world so we are still left with the need to address problems where and when we can get the social and political will to do so. Using finger pointing as a defense has the effect of making the problem seem insurmountable and therefore sapping the will to fix it.
The more genuine admission might be to simply say, "I admit I have shit on my shoe, and it does stink; however, if you are to hold me to account for that, then I demand you also be held to account".
With that approach people have a much harder time seeing the complaint as merely a self-defense by way of finger pointing and it's much more likely to be taken seriously.
This is where many people in the US are probably at on, say, the Trump indictment. Can't really say it shouldn't happen, he has almost certainly broken a long list of laws for his whole career. But that also shouldn't be the end of it, more like "Great start getting a corrupt and lawless politician in jail! Who's next on that list? When does their indictment begin?".
It is most often used as an attempt at a defense by calling out other guilty parties. Yes, we should like to live in a world where anyone calling out a problem or injustice only does so from a place of unimpeachable moral authority. But we do not live in such a world so we are still left with the need to address problems where and when we can get the social and political will to do so. Using finger pointing as a defense has the effect of making the problem seem insurmountable and therefore sapping the will to fix it.
The more genuine admission might be to simply say, "I admit I have shit on my shoe, and it does stink; however, if you are to hold me to account for that, then I demand you also be held to account".
With that approach people have a much harder time seeing the complaint as merely a self-defense by way of finger pointing and it's much more likely to be taken seriously.
This is where many people in the US are probably at on, say, the Trump indictment. Can't really say it shouldn't happen, he has almost certainly broken a long list of laws for his whole career. But that also shouldn't be the end of it, more like "Great start getting a corrupt and lawless politician in jail! Who's next on that list? When does their indictment begin?".