This is one of those issues that seem questionable on the surface, but upon reflection make a little more sense. After all, who are printer manufacturers to limit how their customers buy ink and toner for their legally purchased printers?
Keep in mind, though, that there are numerous scam artists out there who provide shoddy product that provides very little actual ink and that causes real damage to equipment. It’s not unreasonable for printer manufacturers to want to protect against this sort of true “piracy” (which is a term used in the copier world for a very real and very damaging problem).
It’s unfortunate that the casual user and honest purveyor are caught up in the net, but sometimes that can’t be helped. And remember: printers are cheap because the printer companies make their money on toner and ink. You don’t even want to THINK about how expensive the equipment would become if the manufacturers lose their revenue stream from ink and toner.