Agreed. I posted that original idea for discussion and brainstorming purposes, since it was being rumored as a kind of insider "leak". Sorry for any confusion that I created -- I never intended to say that it IS reality. And as I look at the changes I've collected so far, the idea does not hold up. If such a shift is in the works, then it's not yet live - from what I see.
Again, the only factor I see that appears to be active is changed approach to user intention - more SERPs showing diversity. This could result from a re-categorization of frequent query terms, with more of them now being tagged as ambiguous intention.
We often tend to focus on the on-page, off-page and off-site factors, but give very little attention to Google's growing taxonomy for query types. The minus fifty thing is also showing up for another batch of site and that still seems quite curious to me. So far, I don't get the point for many of those.