Hissingsid - 2:29 pm on Oct 14, 2011 (gmt 0)

become more dominated by large powerful sites with massive backlink profiles

I don't think it is because they are large and powerful with massive backlink profiles, those things are just a co-incidence.

They are also semantically rich but focused and benefit from being strong in the broad semantic topic area. If the brand is a synonym or semantically close to the search term then they are given a further boost.