Let's assume, for arguments' sake, that this is 100% true.
* It's true that chalk is not going to harbor any sort of micro-organism on it’s own. However, as people dip and re-dip in the bowl, the chalk stops being sterile because it's touched by sweat, skin, oil, and germs. That bacteria will stick around on bars, climbing walls, in the bowl, etc., and can eventually cause infection and make you ill.
At one point, I developed not one, but three staph infections from a tumbling mat during an extended MMA class. You're probably thinking, "But tumbling mats are plastic. They're inert, a non-metabolite, and sterile, right?"
But, it's not the material that matters. It's the dynamic, open environment in which the equipment is used. The mat I used had been thoroughly cleaned, but as people came and went, bacteria was deposited on the mat and I picked them up. My point is this: Unfortunately, your equipment and chalk bowl do not exist in a vacuum. That's where Primo Chalk comes in.