Not sure that description captures it as it isn’t about getting the community on for any multiplier or amplification effect. But really it is getting something to be useful to a community such that it can be useful to more and more communities of people over time. FB on colleges, snapchat in high schools, nextdoor in neighborhoods all apply. As do tinder in clubbing communities, Pokémon go in all kinds of local communities, Yik yak as it spread on campuses. But it doesn’t always necessitate the people knowing each other before.