I've earned my money by doing seo since 1999. Sure quantity is a function, but only if you do everything else right. In particular, keyword research and long tail.
Have you ever read Brett Tabke's
Successful Site in 12 Months with Google Alone
That is a bit dated going back to 2002, but much of it is still very applicable. Many have taken that route and have success. But it has nothing to do with quantity, if you aren't doing everything else right regarding seo. If that is the case, you'll do a lot of work with little results
Today, I think you also have to consider the time it takes to establish a new site in the rankings.