Yes, Its true that many webmasters that used some not really ethical money-making-techniques did get the warning “your AdSense account will be closed” email. That is simply one of the many efforts for increasing the web quality by Google.
The main reason for banning so many people is the sole reason that MFA Websites with Google AdSense Arbitrage are driving mass amounts of traffic and the low quality MFA websites are generating very high CTR (Clickthru Rate) and this is causing very low ROI (Return of Investment) for the AdWords Advertisers. The sole action of closing such sites is one of the biggest efforts from Google to increase the quality of their AdWords advertising program and lower the advertising costs for many advertising clients and therefore try to attract many new advertisers for their network.
Now the question is should I be afraid of this? Yes I do run some MFA websites but I don‘t do any AdSense Arbitrage and all my traffic comes from organic listings or banner ads which is totally natural and the people that come to my websites are not forced in any way to click on the ads (yes the low amount of content is a reason for high CTR but my statistics show that I don‘t have higher CTR than 40% and average of $30% which is pretty much flag for MFA)…..
I‘m trying to use the tactic of increasing the quality by adding valuable content aka more articles and in that way to bring some value to my visitors. As you know more content for MFA‘s decrease the CTR as people find what they are looking for on your own website and don‘t really click on the ads, but that‘s OK as long as I receive better amounts of traffic each day, the low CTR is compensated with the fresh flow of traffic.
From my understandings Google is going after the big websites that are made only for ad clicks and my MFA network is quite smaller for them to find and to have any value in removing/banning it.
Also yesterday I wrote one nice article/post for the SEO News blog on Google goes after MFA sites with AdSense Arbitrage and you can visit it to see what is the real story under this big wave of banned AdSense accounts.