Instagram and Facebook may have stories but the site is heavily predicated on pride/narcissism arms race with your "friends".
Even your biggest narcissist can only "win" for 24 hours on Snapchat and from what I can see they'll generally tap out of keeping up any facades to try and make others jealous about how (seemingly) great their life is within 4-5 weeks of using it and then join others in appreciating the little things that make life worth living.
Your own personal values and mileage may vary, but they've hit a niche with me.