I guess it depends on which side of the coin you are on. Saving scraps requires space, space that I can use for ingredients or inventory.
Rebatching a soap requires additional time and money. Example...a typical bar of soap without packaging costs me around XXX (includes labor). To rebatch a soap, I will first have to shred it (labor), remelt it (add'l water, electricity and time), and recolor or rescent it (more money). Considering that labor and scent is my highest cost...my costs on that bar have now doubled Now I have to package it (more money). At best I'll probably break even, at worst I will lose money and if that is the case, why not toss the soap and use the labor, ingredients and overhead to make soap that will generate a profit? Yep...I'm an accountant.