I have read this thread with interest.
To me white hat on page SEO is real and definable. In the on-page world, by far the most important part of SEO there is, is cut and dried. There are rules, and following them is almost as easy as filling in the blanks.
Most webpages I see do not target what the owner thinks they do, and they try to force themselves to rank for a term the page does not target with back links. The end result is that your back links are unrelated (as far as a computer algorithm is concerned)
How useful are unrelated backlinks? If you fix your onpage seo, all thiose backlinks will suddenly be related to the page content. Couldn't hurt.
When your onpage is even a little off, the search engines will think the page is about something it is not. It may be closely related, but your visitor is not going to find exactly what they searched for. It's that simple. If you do it right, they arrive and find exactly what they wanted.
People think they get an article, fill out the plugin, and they have an optimized page. They don't craft their content. They don't create quality. Hell they don't even use H tags.
Off page is more of a relative thing. Relative to how most people behave in that niche. If you behave like a typical business in that niche, Google will almost never bother you.
I also think that some niches are just black by nature, because the normal way a site behaves in that niche is already blackhat. MY method would never work for the "make money online", "lose weight", or any of the big niches because people have been black-hatting it for so long that it is normal behavior in that niche.
But generally, you are allowed, expected, and encouraged to promote your business. The Internet cannot exist without links.
You are not allowed to try and influence the SERPS.
Walking that line is the craft of whitehat SEO.