It has to do with splitting the cost of shared resources, I will agree that it's not the same as the OP but I will argue that it is in the same vein and further more that people that are interested in how best to split rent might also be interested in a way to facilitate the collection and tracking of said rent.
Splitwise used to have a link to Venmo but I can't find it now, they do have Paypal integration that you can use (you have to pay Paypal fees though). That said you can of course use whatever you want to exchange money and my roommates use Venmo and Simple Instant (and goods/services like groceries/utilities in their name) to pay each other.
Edit: Also see Splitwise's rent calculator: https://www.splitwise.com/calculators/rent