No that's not how you do giant chips. Even at the scale of CPUs, there are enough bad parts that it's uneconomical to throw away chips. What Intel/AMD do, for example, they make 4-core chips. If one core doesn't work, they sell it as 3-core or 2-core system. If some of the cache doesn't work, they sell it as a lower cache version.
In the case of Cerebras, they have disable the bad blocks to get chips that actually work.
Sure, but you still end up with area that is critical and shared and doesn't yield to this strategy, and you also end up with defects that are bad enough that you still can't employ a wafer with portions turned off.
So, someone like Cerebras has to both make as little critical as possible and buy much more expensive wafers with lower defect rates and still get only moderate yields.
When you buy wafers, particle counts at sizes are specified, along with all kinds of other properties-- some determined through non-destructive testing (and can be used for binning) and some through destructive testing (and can be used for characterizing lots).
But remember the cpu market is extremely price sensitive and Intel/AMD have such huge volumes. Manufacturers of large chips don't necessarily need to worry about the extra complication of binning in order to yield.
In the case of Cerebras, they have disable the bad blocks to get chips that actually work.