That's the thing. If you've got a cluster of money sites on one reseller account, and all of them have links from free blogs as part of the SEO strategy, won't that look suspicious?
Currently, it works. Of course, Google can change at any moment though.
It's understandable that there are sites out there which have all sorts of sites linking to them, but I'm pretty sure that free web properties, article directories and so on linking to all your money sites on one hosting account will somehow make all of your sites look funny in the eyes of G.
It absolutely CAN look funny, if you can call penalties "funny", if you link from low quality free blogs / article directories. By low quality, I mean unmoderated domains with zero PR and zero high quality backlinks to the domain. The average AMR submission, or pligg submission, will toast a new website.
As it turns out, free websites are actually some of the most credible websites you could possibly get backlinks from. Look at http://www.seomoz.org/top500 ... domain moztrust on blogspot is 8.73, domain moztrust on wordpress.com is 8.59, tumblr.com is 8.16, weebly.com is 7.83, webs.com is 7.68, jimdo.com is 7.24, fc2.com is 7.36, tripod.com is 7.71, and on and on ... tons of the sites you can get links from with free blogs are on the top 500 websites.
Which would you rather have, a backlink from a website that is starting out with moztrust of 8.73? Or starting out with moztrust 0?
And how else are you going to build your tier 1 backlinks? Of course if you focus on 1 niche and work hard on it you will get unique backlinks with time but if you're working with multiple sites, getting those unique backlinks becomes much harder.
As it is, building backlinks to a free blog tier-1 network is a good tactic. There are other tactics of course, if you have the money.