It really depends on how you define appliance. One of the most common definitions is "The act of applying; application; An implement, an instrument or apparatus designed (or at least used) as a means to a specific end (often specified);"
For most people then a computer is an appliance and has been for more than a decade. It's a device that accesses the internet or does word processing or spreadsheets. It's not a general purpose device, you can't open a sardine tin with it, it won't physically take you places.
I know this flies in the face of aOS 4.x but it has a purpose beyond loading your favourite GUI. In fact most people don't even have a favourite GUI, they just want to read Facebook, or type a paper. Computers exist to do something with. Organise your photos, find information, etc. Computers are the dam most useful appliance I've ever seen. The are a means to an end, not the end itself.