I agree and disagree. Easy management of server apps IS a hard part. Domain registration, DNS management and port-forwarding are ALSO hard parts.
For 99.99% of the humans on earth, their primary computer is a smartphone. Anything that they can't do with a smartphone-like interface is hard, bordering on impossible. Even on the smartphone, there is a huge app complexity hurdle - sure some folks will use complex apps, but most people won't go much further in complexity than a subset of the apps that come with their phone. They'll add apps because it is easy, but they won't actually use apps that are too hard for them to use.
These days, those same majority of the population might be annoyed at having to use an app to manage their wireless headphones, printers, smart appliances etc etc.. but they WILL do it. And they CAN do it.
Effectively all of those devices are technically servers too. Back in my youth, we'd call a printer connected to a network a "print server" and it was often a standalone device that connected the printer to the network.
There is no inherent reason that managing a fairly capable server, backups, DNS, VPN tunneling, port forwarding etc can't be as simple as "a basic app." Yes - a lot of limitations on what is theoretically possible will be imposed. Limitations and defaults will need to happen in the background to keep it simple. But it can happen.