Using that logic, many computers over the years have run pirated software, so would you want to make computers illegal? How do you define the threshold for legitimate usage?
Let's make it 80%. Would you agree that 80% of all the digital copies of ROMs out there are pirated? Given the prevalence of cheap console emulators on AliExpress I would not be surprised if that number was even higher.
Many of the legitimate cartridges are sitting in landfills.