Hey awesome questions, thanks! The idea behind this app was not to replace either your camera app or your messenger app, so for any of those cases you mentioned i would simply use camera and then share image to multiple friends.

The idea behind this was that there are certain use cases when you simply know you just want to send a picture to someone, and thats why you are taking it.

So the question i tried to answer with this prototype was - when does a certain use case become so frequent that it requires an app of its own. Perhaps this is the biggest questions of them all, since we can see all of the big guys growing slowly out of the app size and having additional apps for different use cases and needs.

When I first saw this it reminds me of Bolt by Instagram. Also what if a person has 4000 Facebook friends?? How do you select whom to send to? But I like the author showing the thinking process though.

I'm not the author (hopefully he'll see this and provide you with a better reply) – but I don't think the point was to build a perfect photo sharing app. It's an UX exercise that documents the design thinking and process from its planning stage, through mockups and finally building a prototype. That's why I thought it is worth sharing.

(BTW, I think the issues you mentioned are really minor and easily solvable.)

Thing is none of my friends are on Snapchat, but all of my friends are on Facebook.