If you think Designing and developing a product is one level of complexity then marketing is more than that. Any product you develop needs 50% of your effort then marketing needs the rest of the 50. Most of the products fail when it doesn't reach to the people it needs to. So the strategy came up to not only do marketing, but also ask the marketers to involve the people to refer their family and friends. It doesn't stop there. We can involve those people to work or refer others for us even if they don't buy a product. That's called as Multi Level Marketing.
This technique will not only grow the product sales, Rather it will also going to create lot of 'work from home opportunities and these opportunities are termed as home based business network marketing. For many People this kind of Network Marketing program brings amazing work experience and improves their sales strategies. For e.g. Amway is one of the very good examples for multi level marketing. If you cannot buy a product, but still you can recruit a sales person and refer them. But this needs patience and consistency to result expected outcome. But rule will be, before you market any product, Try to research about the product and understand better to promote well.