Having no margin of error on these SKU's would be terminally dumb, but having tight error bars isn't necessarily a bad thing.

Being able to sell bad batches of product takes some of the sting out of failure, and past a certain point you're just enabling people to cut corners or ignore fixable problems. Having a tolerance of 1 bad core means if I think I have a process improvement that will reduce double faults but costs money to research and develop, aren't I more likely to get that funding?