it seems that there is a google ban panic between website owners these days, I wonder if google is really banning sites aggressively or they just claim that. Google can't ban sites depending on algorithm decision, does google have the resources to evaluate each site to be duplicate or not? it seems like all they can do is change the rules from time to time to scare everybody, and the results for every time will be more sneaky techniques and better ways to hide things for people who want to make money. Now they want to track paid links, by changing the report paid links page, also they started sending people notifications about having bad links pointing to their sites you can read the article here: http://searchengineland.com/googles-spam-report-page-biggest-refresh-in-years-88349 Isn't this too much for the webmasters to take? all serious businesses do buy links, and do game the google serps. for ex. how would a site about blinds gain natural links? by publishing valuable articles and contents and wait for people to link to them? lol
Google webmaster guidelines are pretty simple, when they say, don't buy links you don't buy, because somebody of your competitors may report those links.
So, according to what you said a website like eHow, ezinearticles, Hubpages, Squidoo ....(add at least 1000000 more) didn't buy links when they started, they just waited for people to link to them?!! The fact is every single business do hire SEO companies to optimize their site, and this will involve buying links. only they manage to stay under the radar. What I think is that google targets sites that have low quality content and buy links to rank well in SE. As long as links are commodity they will be sold, and this cannot be stopped by any SE.
There's no fault to buy links, you should pay attention to the ammount and buy from related websites.