Because there's never a guarantee the app is open, especially on mobile.
If we take your Snapchat example , if one user is trying to send a message to another and their app is closed or their device is off, where does the message go ?
On the desktop you have the luxury of mostly running in the background to pick up the ping, but it's almost never the case on mobile.
If we take your Snapchat example , if one user is trying to send a message to another and their app is closed or their device is off, where does the message go ?
On the desktop you have the luxury of mostly running in the background to pick up the ping, but it's almost never the case on mobile.