I think it's hilarious that you think it wouldn't work. Please explain to me why it wouldn't? I'm ranking #4 on a 150k exact search per month term.
I've seen a ton of sites employing this tactic with domains they own, or buying links in such domains.
It lasts at most 1 mth, before google slams them down hard.
I have enough experience I'm willing to wager that this kinda thing is both a waste of time, and an expensive misadventure.
Show me an example to prove otherwise and I'll consider it.
This behavior is "viagra" niche material... as that's most often where I see it.
http://www.majesticseo.com/reports/site-explorer/summary/www.viagracheaprx.com?IndexDataSource=F
I've done the PR filtering thing on a few sites... it helps, but no more than building ANY site helps.
I'd rather have a PR7 backlink from my list of blogs that autoapprove and are d0follow anyday... and this requires no monthly fee or domain price, or backlinking or building up of the site.
If your network is FANTASTIC then sure... but it'd take years to build such a thing... and a hell of a lot of investment and even more $ in the way of time.
You would be a lot better off creating a virus that drops links into wordpress blogs.
Also the whole unique IP thing for each domain (if you believe in the google valuing this thing... which is somewhat suspect I admit) You're talking $500-1000/mth just to maintain the damn network.
You COULD sell blogposts/rolls to pay for this... but it all sounds just so blah to me.
How much is an autoblog worth? Few hundred dollars each? x 500... there's a lot better ways to spend money.
From my experience people who do this use it to MAKE money (sell the links)... that is legitimate. But to help a site? not legitimate.