Why Are SNES and Genesis "16-bit"? [closed]

As a hardware and software engineer, I'm mystified by the claims that both the SNES and Genesis are 16-bit consoles. As best I remember the stats:

SNES

• 16-bit registers and arithmetic
• 8-bit data bus
• 8x8-bit multiplier
• 16/8-bit divider

Genesis

• 32-bit registers and arithmetic
• 16-bit data bus
• 16x16-bit multiplier
• 32/16-bit divider

I don't see any reason the Genesis would not be considered wider than the SNES. If we use the fairly common definition that the bit width is determined by the narrowest part of the system, the SNES would clearly be 8-bit and the Genesis 16-bit. If we define the bit width as the (equally common) size of arithmetic operations, the SNES is 16-bit and the Genesis is 32-bit.