These things are not general purpose computers. They are custom fabbed hardware with vendor supported software and are not user repairable. They do one job and they do it well. At the end of their service life you replace them.
My iPhone is an appliance and I prefer it that way.
A Juniper firewall is an appliance.
A NetApp SAN is an appliance.
An Ooma VOIP phone system is an appliance.
A Kindle is an appliance.
A Nest thermostat is an appliance.
These things are not general purpose computers. They are custom fabbed hardware with vendor supported software and are not user repairable. They do one job and they do it well. At the end of their service life you replace them.
My iPhone is an appliance and I prefer it that way.