By "they" you mean a third party vendor; not Canon per se - correct?
Printer manufacturer's make lots of money on ink cartridges and go to great lengths to prevent third party cartridges or refilling of original cartridges.
Google "Canon refillable ink cartridges spongeless" and you will find numerous links.
However, refills may void your printer warranty at best. At worst the refills may damage your printer.
Not recommended. Especially as so many such products are cheaply made with little or no attempts to maintain some Quality Assurance. And their fine print probably absolves them of any liabilities if things go bad.....