They were after publishers that use adwords and adsense for arbitrage reasons. Not only that reason a good percentage of the advertiser/publishers that were banned IMO were not using the recommended site guidelines for landing pages.
Yep. Its not per say if its unique or not, its the point that the site has no value to the internet. If your website has no value to what is already out their and you fill it with adsense then it prob MFA, and could get kicked from their program.
Mfa sites are profitable for google. They convert well for adwords advertisers because these sites usually get targetted traffic. From generated mfa websites google supplies traffic to advertisers for many obscure keywords that they wouldn`t get otherwise. My guess is that mfa sites will never die because for who it would be useful?