Re: industry subpar knock-offs
You need a 64-bit CPU to access more than 3 gigabytes of RAM, though (same as with a PC)
You seem to be confusing address bus width with data bus width, though the definition of "N-bit CPU" does seem to have changed over the years. You can connect a humble 8-bitter to any amount of memory you want if your fancy takes you, though it's often sensible to have register and data bus width the same size as address bus width for efficiency.