Some people are posting these very in-depth essays about Snapchats success, as if there was some deeper meaning to a picture that doesn't reappear. To be perfectly frank as a young adult, Snapchat was great for flirting. As more friends joined, I also found it to be a fun way to talk to friends. There is nothing more to it than that. Came for the sex, stayed for the filters.
There is something novel about a transient social network that only really exists when you're actively using it. People's behavior changes when what you say and post doesn't follow you forever, when you are rewarded for interaction rather than agreement. It's made people more genuine, they're less guarded, there's less virtue signaling, there's almost no political drama, and it's more personal.