Tinder could be using Facebook to make sure that profiles created on it are real since Facebook does a good job of removing Fake profiles. See why some people create fake profiles on social networks.
Many applications use Facebook's sign up option to make it easy for people to register. According to conversion rate experts, the less steps required for registration, the more people will register.
Tinder uses Facebook and Instagram to grab some profile information. This helps Tinder have authentic data and also makes the process of filling the information in the profile easy. See why Tinder became successful.
Tinder grabs many information from Facebook, such as interests, in order to provide better matches for people.
According to Tinder app, the Facebook friends of a person are compared to the friends of the person's matches to display common connections. See why Tinder is addictive.
Tinder uses Facebook to prevent people from lying about their Age, work or interests. Grabbing the information from Facebook ensures their reliability to a great extent. See why you aren't getting any matches.
Facebook log in is so popular and people hardly question their privacy while using it. This made it a good choice for many apps, including Tinder.