The Intel 80386DX did NOT have any 80 bit instructions at all, the built in math co-processor came with i486.
You're right, I misremembered.
And in that regard, the Databus is a very significant part, that directly influence the speed and number of clocks of almost everything the CPU does.
For those old processors, yes, that's why the 6502 was 8-bit, for modern processors, though? You don't even see it listed on spec sheets. Instead, for the external stuff, you see number of memory controllers and PCIe lanes, while everything internal gets mushed up in IPC. "It's wide enough to not stall the pipeline what more do you want" kind of attitude.
Go look at anything post-2000: 64 bit means that pointers take up 64 bits. 32 bits means that pointers take up 32 bits. 8-bit and 16-bit are completely relegated to microcontrollers, I think keeping the data bus terminology, and soonish they're going to be gone because everything at that scale will be RISC-V, where "RV32I" means... pointers. So does "RV64I" and "RV128I". RV16E was proposed as an April Fool's joke and it's not completely out of the question that it'll happen. In any case there won't be RV8 because CPUs with an 8-bit address bus are pointlessly small, and "the number refers to pointer width" is the terminology of . An RV16 CPU might have a 16 bit data bus, it might have an 8 bit data bus, heck it might have a 256bit data bus because it's actually a DSP and has vector instructions. Sounds like a rare beast but not entirely nonsensical.
The reason you're getting downvoted is because you're saying that "64-bit CPU" means something different than is universally acknowledged that it means. It means pointer width.
Yes, other numbers are important. Yes, other numbers can be listed in places. No, it's not what people mean when they say "X-bit CPU".
RV128 exists. It refers to pointer width. Crays existed, by your account they were gazillion-bit machines because they had quite chunky vector lengths. Your Ryzen does not have a larger "databus" than a Cray1 which had 4096 bit (you read that right) vector registers. They were never called 4096 bit machines, they Cray1 has a 64-bit architecture because that's the pointer width.
Yes, the terminology differs when it comes to 8 vs. 16-bit microcontrollers. But just because data bus is that important there (and 8-bit pointers don't make any practical sense) doesn't mean that anyone is calling a Cray a 4096 bit architecture. You might call them 4096 bit vector machines, and you're free to call anything with AVX2 a 256-bit SIMD machine (though you might actually be looking at 2x 128-bit ALUs), but neither makes them 64-bit architectures. Why? Because language is meant for communication and you don't get to have your own private definition of terms: Unless otherwise specified, the number stated is the number of bits in a pointer.