It’s called the ‘inner platform effect’. They are basically replicating parts of the underlying platform (the OS in this case) inside their own application, until the application turns into a platform itself, one crappier than the one below it. You see this happening with web browsers and ‘web apps’.

Then maybe switch to a better OS / Window manager?

What would you say determines whether a kernel is a Unix kernel?

Not what, who. And the answer is The Open Group,

Which is how fast?

And what is the memory bandwidth on these APUs?

you’d definitely be able to do it cheaper with PC hardware.

You can get a GPU with 192GB VRAM for less than a Mac? Sign me up please.

Sounds like a case of X-Y problem

No, the terminology sounds right to me. The term front-end and back-end are used in other contexts than building websites.

For example, the term is used in compilers, where the front-end takes code in a programming language and translates it to an intermediate representation (IR), and the back-end takes the IR and translates that into machine code for a specific architecture. A compiler like LLVM has many front-ends and back-ends to support different languages and architectures.

The term applies to many things where there is a multi-layered architecture.