One problem that a new site/app would face is that, to be useful, it would need a geographical density of users. If you have 100k people signed up, but they're spread out across north America or Europe or wherever, then very few of those people will ever meet irl. So at best you have a messaging site for lonely people, but more likely just an unsustainable business. Achieving the necessary user density needs scale and advertising budget.

Something highly local might work in a big enough city like Paris/London/NYC.