I think I understand your frustration, because you hear, on one side, “you have to build a platform” and then if you interpret the post linked above as “don’t talk about your writing,” it seems to negate building a platform. However, the way I interpreted the blog was a reminder that what you put on the web is out there for all to see. It is a representation of you personally, and professionally, but many don’t treat it as such. They use it as a format to whine, and while we all need to whine sometimes, there is a time and place to do it, and it isn’t on a blog where people who can influence your career can see it.
I thought it a good point about not talking about how long you have had your book out there, or how many people have rejected it. I never thought about how an editor might consider having that knowledge, or how it would hamper an agents ability to sell the book.