As a home user, you can use a PtP link like this to share your internet connection with a neighbour, friend or family member! Saving you money as you will only need 1 internet connection!
Businesses tend to have their own servers and internet connection which they need accros multiple buildings. If you have a few buildings nearby you can have all of your servers in one building and one internet connection, then use a PtP link so that all buildings have access and WiFi!
Commercial companies often have sites that have CCTV cameras covering the whole area, or they just want WiFi throughout the site. PtP links also allow these systems to be connected together so that you have one central CCTV system for the whole site and WiFi too, no matter how large.