In this video, a Canon print cartridge is opened up and revealed not to contain the meagre 11.9 ml (0.4 fl oz) of ink it is advertised. The proposed solution is to buy a printer designed to be manually refilled with bottles of ink (such as the featured Epson EcoTank ET-2850), though it has only been tested briefly.
The downside of sponges is that scammy printer ink companies abuse them to mislead customers. The upside is that they prevent problems that storing a liquid and possibly moving it back and forth in a jerking motion, as inkjet printers often do.
A good printer company, if such a thing exists, could make much more reliable printers with sponges then with tanks. Sadly, like their products, all printer companies are evil.
I’ve always ordered ink from inkjets.com because it’s cheap and their cartridges are completely clear so you can actually see that they’re full of ink like you’d expect.