That would yield a mess, historically. For instance, the 32-bit IBM System/360 had a 24-bit address space. The 16-bit Intel 8086 had a 20-bit address space. The

That would yield a mess, historically. For instance, the 32-bit IBM System/360 had a 24-bit address space. The 16-bit Intel 8086 had a 20-bit address space. The 4-bit Intel 4004 had a 12-bit address space. It doesn't make sense to call the 4004 a 12-bit processor and the System/360 a 24-bit processor.