And, why not use your combine to pull it?

Well, it is not quite the same thing, but the idea, as I see it, is that each tool is specialized for a purpose, that is the point of the above sentence.

I had an IH 4500 (think that was the right model number) that was heavy enough that several people said it was "almost a chisel plow".  The idea was that it had heavier shanks and could do deeper tillage.  I added shanks to the original so I had less ridging, but I still had the advantage of the heavier shanks, as I had problems with breakage on the previous lighter model chisel plow.

You could change your chisel plow into a field cultivator (in my opinion) but (in my opinion) you would need more shanks so the ground would be leveler.  The shanks on a chisel plow are spaced wide, and do not level the ground well.  You also would have more problems with weed clearance if you added shanks, as most field cultivators have their shanks spaced wide on several rows of bars, where a chisel plow is usually three rows of shanks, sometimes two.

There would also be a problem of whether your chisel plow would be wide enough to be efficient, as most are designed small so they can be pulled deeper than a field cultivator.

In short, this is a question that could be answered yes, but is it really practical?