See, for a long time, the traditional offline methods of making MLM work were just too difficult for the average person. There was too much time investment outside of the home, too much cold-calling and too many companies that encouraged people to "recruit" friends and family members.
The point of a home-based business is to work at home, right? This was virtually impossible under the old way of doing things.
Multi-level marketing has "grown up" a lot in the past decade, though, largely due to the influence of the Internet. The products and commission structures have improved and most of the 'scams' have been shaken out since word-of-mouth on the Internet can take a company down fast.