Who cares about used games really just spend the extra dough.
People who don't have the extra dough or are simply unwilling to spend it unnecessarily.
Seriously though, the Switch being cartridge-based is a blessing for used games. Far less likely to wind up with a screwed up cartridge than a scratched disk. I'll be being pretty much all my Switch games used if it is sold complete (with case and no used-up DLC vouchers), and can save me at least $5.
The chances of getting a banned game are
quite slim considering hacking consoles is not really mainstream. Even out of people who do hack consoles, what good reason is there to dump a game and re-sell it? You might as well just pirate it from the internet (assuming a public release is available) instead of going through the hassle to get a physical copy. Of course, I generally don't play much online so I'm not that worried about getting a banned game anyway. As long as it doesn't get my Nintendo account banned, I'm not concerned.
That being said, if I ever get Splatoon 2, that is one I most likely will get new because I don't want to take my chances on a game that is 90% online. I can't see a whole lot of Switch games being as heavily online-based, though, aside from maybe some F2P games which obviously don't have the same risk.