As for the mobile only situation I would say this is a good business decision to minimise (not eliminate) spam accounts and possibly would be a good idea if people get indexed into search or people share this will promote installations. It worked well with IG this concept so I'd say in its early conception it was a wise move.

It's also very obvious that this team has experience with social networking.

Now for my negative comment, I'd say gaining traction in the app era of today is hard when it comes to social networking due to the reason is that everyone is bombarded.

I would recommend focusing on the need or the feeling of why one would want to open the app again which as of now I am finding hard to see personally. This is the most crucial part and All energy needs to put towards exposing the app in an organic way with that need.

As much as of a no brainer it sounds we have seen previous start ups fall from this lack of identification