It isn't the mutual selection alone, but that feature in combination with swiping (basically a first impression) and inability to go back make it substantially

It isn't the mutual selection alone, but that feature in combination with swiping (basically a first impression) and inability to go back make it substantially different than dating sites. To my knowledge dating sites usually have pages of profiles you search though. If you see someone you select, but say you go through 5 pages and no one catches your eye but you're out of matches. You may be willing to go back through and lower your standards to make some matches. This is also aided by Tinder being a more dynamic app. The number of people that are active(discoverable) changes day to day, whereas a dating site is essentially static; with only new users adding more potential matches.