http://www.mrmoneymustache.com/2011/05/23/get-rich-with-owni...
http://www.mrmoneymustache.com/2011/06/29/good-times-for-lan...
It seems like you are being reductive and misleading in characterising his position - First you argue he won't dare talk about rental income, then when examples emerge of him doing so you say that he is exhorting everyone to do it!
MMM talks at length about other sources of income generation too, but let's just ignore those:
* Stocks: http://www.mrmoneymustache.com/2011/05/18/how-to-make-money-...
* Peer-to-peer lending: http://www.mrmoneymustache.com/2013/08/26/the-lending-club-e...
* Carpentry: http://www.mrmoneymustache.com/2012/04/27/nicer-legs-and-som...
As for frugality this may not be a path to financial security for many but it sure is a refreshing departure from the "more, more, more" of modern life.
God he does p2p lending also. Yuk.
However let's get this straight, there are plenty worse than him out there but I do hate to see his holier-than-tho "be frugal" when in fact he's a rentier who can be "frugal" because he's a rentier.