Lead generation is the practice of ranking a web page for a search phrase then selling leads from that page. Companies like Yelp and HomeAdvisor are examples of lead generation businesses.
Yelp and HomeAdvisor rank web pages for local search related keywords.
Their business model depends on ranking for search phrases then selling leads from the Google Local Search traffic (sometimes via paid advertising).
Rank and Rent is a variation on lead generation. Rank and Rent rents the entire website and all the keywords that it ranks for to a single business.
This is good for the business because the business can benefit from the Rank and Rent website as well as from rankings from its own website.