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?
We'll start to see high-binned next-gen Apple Silicon parts moving to the MacBook Pro, and Mac Pro, and lower-binned parts making their way down-range.
That could make sense for Apple; the M1 is already ~1 generation ahead of competitors, so axing a bit of performance in favor of higher yields doesn't lose you any customers, but does cut your costs.
Plus, they definitely do some binning already, as mentioned with the 7 vs 8 core GPUs.
Even Apple is susceptible to it. But Apple doesn't sell chips, they sell devices and they can eat the cost for some of these. For example if a chip has 2 bad cores instead of selling a 6 core version Apple is probably just scrapping it.