One thing I'm wondering about is how much people didn't like them because I was saying controversial things while also saying, "I will give more justification for this later," which would have been avoided by not splitting the posts.

I didn't downvote them, but think they would have been a better fit for discussion than for main. While a summary of research or case studies on nutrition would have made a good post for main, I don't think a criticism of a popular book on nutrition (that I haven't read nor even heard much about here) is as generally interesting and useful.