Why would they? The privacy problem with Facebook is its size and the amount of personal data it integrates. If you're privacy conscious, using a stand-alone dating site is fine because the data is more siloed. It's also more practical to setup a burner identity on a special-purpose site than on a one that tries to be your online identity and social graph.
I never used tinder, but I thought about it. Part of that plan was to create a burner FB profile for it.