I think you’re right, but the importance of some history to the credibility is higher in certain areas. If I write an article and post it on HN, then yes, I don’t think people here care too much about my public history, procided that the article is interesting.

But if I decide to write and sell a book or produce a paid course, then having no history related to the field I’m trying to be an expert in feels pretty sketchy.

I can say for myself: when I’m considering buying a book or a course, I research the author.