Putty rubbers are a serious nuisance.

I won't deny the fact that they are so wondrous at rubbing out marks that others erasers only make worse by smudging. I won't deny the fact that they are kneadable and thus very practical.

However- the problem arises when I break off small pieces to work on fine details. You see, I've broken off so many small pieces from the rubber that it is seriously about half the size it was when I bought it.

So it's kinda weird when I'm rummaging around my desk and find little pieces of what I think is Blu-Tak.

Anyway, so yes, that's why they are a nuisance. They just want you to buy more and more and more of them as you deplete the rubber supply.
Bloody capitalists.