I think one of the confusing things is ARM holdings doesn't sell physical chips. They sell a spec (verlog code I believe) that can be turned into a chip. Add some usb, memory, video card, maybe wireless and you get a system on a chip.
ARM sells many things, that many different customers use.
One is a license run the ARM ISA, so you can design a chip from the ground up. Another is a license to produce a reference implementation of a single processor design. Others peripherals and options exist too.
So, in short, a microprocessor architect might be needed to build an ARM chip, depending on how one was going about it.
and to be clear, what Apple has is the ISA license. Apple's ARM CPUs are not just the reference design from ARM. I'm not enough of a hardware person to know if they are modifying the design or have implemented the ISA from scratch, but their chips seem to be significantly faster than anyone else's so they're clearly doing something smart :)
Except that it isn't short. ARM licenses their architecture which you can implement but that implementation also must pass a verification test and you can neither add anything nor leave anything out. ARM also licenses IP cores in its traditional fabless role.
There are about 15 architectural licensees. Apple and NVidia are architectural licensees.
