Surprising data on the growth of K12 online learning

I have been doing a lot of research on online learning lately. I've read several reports on the state of online learning across the country and around the world. Most of what I have read I had heard anecdotally from other sources. One statistic, however, shocked me:

Although online enrollments have increased by 40% in 2009-2010, two state virtual schools, North Carolina and Florida, account for 96% of the net growth meaning that the total enrollment increases and decreases in other state virtual schools amount to only a 4% increase.

Source: Keeping Pace with K-12 Online Learning, The Evergreen Education Group, 2010. 

I am now struggling to evaluate the complete dominance of the online market by FVS and NCVPS. Is this dominance a good thing or is it stifling innovation and competition? Why have FVS and NCVPS been so successful?