Grant's comments about Adobe's ranking for [financial services] don't necessarily apply here. Note that I said above: "where external inbound links matter." Sometimes they matter, and sometimes they don't.
I didn't say, "where topically relevant external inbound links matter," though, if I had, that wouldn't be changing the point I'm making. External inbounds may matter on some searches and not on others. As I've posted elsewhere, I think that topical relevancy may matter on some searches and not on others.
Grant's example, though, was an extremely bad one. Checking the Adobe Financial Services page on Yahoo Site Explorer, I see that it's got 274 external inbounds from other domains, including some clearly related to financial services.
The page is also fully integrated into the Adobe site. It shows 4,440 inlinks from adobe.com. Several of these are from PR10 pages, with anchor text reading "financial services" in the main nav.
This is not about some tiny little almost-hidden footer link giving it some PageRank... albeit, on the Adobe site, such a link from the home page might suffice for a great many searches.
I can't tell how truly competitive these "massive phrases" are. I also don't know whether or not these top sites that you're talking about are 800 pound gorillas and how much "juice" those footer links might be transmitting.
For most sites, though, this kind of detached, low quality gateway approach isn't likely to be a good long term strategy.
Incidentally, are these top 5 competitors related to each other? The fact that they're all using the same strategy suggests that there is common ownership.