Yeah, that's what the CIS company told me. They said their goal was to copy the model of the HP OEM cartridges exactly, which use the mixed ink types. But he did say that I could replace the ink with a universal dye based set.
Also, prior to this, I was looking into a large format printer to do printing on vinyl for stickers, and vehicle wraps. The printer I was looking at is an HP with UV dried inks, but the guy told me I would have to seal the vinyl or coat it because the black ink would just wash off. At the time I thought that was very strange because I never heard of a UV dried ink that was not waterproof. Turns out it's the same thing, they use a pigment ink on the black and dye on the colors. Apparently they do that on all their printers. I'd really like to know why HP did such a stupid thing.