Disabling "healthy" cores, when you don't have enough lower quality chips is absolutely the common practise that chip manufacturers like Intel and AMD do. And there are other performance metrics, not just "hard" count of working cores to decide for the final products - some chips need more voltage than others for the same stability etc. The point is M1 Pros are not some precious gems that has to be sold at a certain level - they are tools/parts that allow you to scale to sell what customers want the most.
Apple's problem is not that they would have to bin more than "you seem worthy", but that they have $1K base model "everyone" wants, $2K base machine a lot of people want, but $1.3 machine than not a lot of people want, because it's too similar to the one at $1K and also can't be priced higher. But there are lot of people that would get $1.5K machine if the insides were better than 1K and worse than 2K. You can make a detail configuration to up ram, ssd, etc, but you're telling me there's no space for a $500+/- difference in base models most people buy? Not having a desirable model within $1000 difference is a huge deal. Not to mention there could be other benefits - you just need M1 Pro (worst of them) and sell it meaningfully in MBP13 with little modification, less parts shortage etc. To make 14" for just $500 more you need everything new. It even might be much easier to make M1 Pro MBP13" and sell it with better margin that 14" base.
