You are ordering something that you could simply go a kilometer down the street for and then return the next day.
Yes, I can return it the next day, having made a choice between staying up later than I want to in order to watch a movie because I have a real life including a full time day job and three kids who all have to be put to bed and well asleep before I can settle down to watch a movie OR returning it unwatched because I never got a consecutive 90-120 minutes in front of the TV.
Or I can order it from Netflix, keep it as long as it takes to actually watch the movie or show, and NOT pay 3-4 times the original cost of renting the disc because of late fees. And it's nice to just drop the red envelope into any mailbox on my way to or from wherever it is that I have to go anyway, rather than scream up the street to the exact store I rented at (even though its a chain) at two minutes to closing time so I don't get charged for another whole day.
Yes, convenience is the downfall of civilization.