How is he supposed to KNOW that the bits in the cartridge are correct?
Radiation and high-temperatures still effect ROM memory. Otherwise, why would we need rad-hardened ROM memory on satellites? And what is space? Just a more dangerous version of what we have on Earth--but Earth still has some radiation. Now add DECADES of sitting around absorbing background radiation, with periods of sitting thrown around on top of someone's table under hot sunlight.
There's a reason super-long-term storage is not as simple as burning a CD.
Now, yes, yes, the practical cure of things like boot loaders, ROM hacks, poor early dumps, and all that crap. Sure. I'm clearly NOT debating that. But tiny artifacts in sprites? Single bit changes in code? Maybe not so much...
Bullshit. You have no idea what you are talking about.
Mass manufactured Carts use mask-programmed ROM devices. Such devices are literally hardwired during fabrication with the bit pattern using a metallization layer. EPROMs are only used for Prototypes because compared to Masked-ROMs they are hideously expensive. Masked ROMs don't lose their bits. The only way to get a bit flip there would be from de-capping the device an physically altering the mask. In ROM failures part of the address decode logic or an I/O line are damaged, from over-voltage, or static discharge. That kind of failure would make a Cart completely dead (crash the CPU, or the graphics would be mangled.
Rad-hard ROMs used in high radiation applications have specially designed transistors in the decode logic to prevent reading the wrong word in the array. The array of bits is just a mask of metallization on the die that wires up the 1 or 0 for each bit cell. Those bits will only change if the array is mechanically damaged.