I think you're touching on an important point about persuasion. I'm listening to a book on archaeology by Kenneth Feder called Native America. It's a wonderful book about the peopling of the Americas and the lives of ancient peoples through the study of the things, and contexts, they left behind. It begins with a call for better public outreach, and a critique of how poorly archaeology often communicates with the general public.
But he also spends a lot of time being sanctimonious and beating a few dead horses. The points are important, for example, emphasizing that people were here long before Europeans “discovered” the Americas, but after a while I find myself thinking trust the reader to understand your original point. You don't always have to return to the same injustice to make clear that it matters.
I think persuasion is really important to consider when you're trying to reach a general audience. Subject-matter experts are understandably frustrated by the misconceptions, injustices, or bad arguments they encounter over and over again, and I imagine it can feel like this is their chance to finally correct the record. But in the long run, that tone can alienate a pretty large group of readers-including people who already agree with you.
Sometimes I think advocacy writing gets more focused on signaling, “I understand the stakes and I am firmly on the right side of this,” than on making the most compelling or effective case. And ironically, I think that can make the advocacy less persuasive.