A solo owner of a business has his own resources. By adding a partner - the partnership now doubles its resources. If a bank just takes in money and loans money out that bank is using its resources for hopefully a profit. If that bank partners with a credit card company, that bank now reaps the benefots of expanded markets and more profit and income. Partnerships are about doubling, and stacking resources of all kinds, legal - marketing channels, expanded distribution, removal of barrier of entry into new markets in some cases. These are just examples. Another similar examole is Susie has a dog walking business and partners with a dog groomer business, they both will expand resources and potentially become more profitable.