boils down to security and being able to punch through firewalls and NAT which are almost always internet facing in a average home consumer network. Really there should be a protocol to solve this problem that is industry wide. I should be able to talk directly to my home network without having to having to connect to a server to route data through that. The solutions now are to create a VPN, but it should be simpler than that. I should be able to securely talk to my home network and punch back through that firewall if I have a token or auth and I should be able to easily generate that auth and I should be able to know where my home network is from the outside.
If someone could solve this problem, it would considerably reduce costs for consumers, because it would take the servers and control of companies out of the loop. You could talk directly from your phone to the home network without a server in between. They need to develop a protocol for this and make it a standard on home networking devices.