Why can’t there just be one simple solution for this which is peer-to-peer? Why does it have to depend on the cloud? Peer to peer solutions are more difficult

Why can’t there just be one simple solution for this which is peer-to-peer? Why does it have to depend on the cloud? Peer to peer solutions are more difficult to build because there are more problems to solve: * Peers need to be in the same network (same Wifi, Internet, etc.). If they are not, a connection needs to be established in some way. * Peers need to know how to reach each other. How can they exchange addresses? * Network/OS needs to allow exchanging messages (NAT, firewalls, proxies, ...). If they can't, then what? All of these are complicated and have lots of error cases. Cloud-based solutions make some assumptions to simplify the problem space: peers have a working internet connection, they can use DNS to look up addresses, and can reach a centralized server, usually via HTTP. It's even better if they are browser based, then peers don't need to install a new client. As Bluetooth and Airdrop show, things don't always need to be cloud based. But also, as Bluetooth shows, it's really difficult to make it work seamless.