Comment by ajb

Normally yes. But they're using a whole wafer for a single chip! So it's actually a good idea.

I guess the issue is how do you design your routing fabric to work in the edge regions.

Actually I wonder how they are exposing this wafer. Normal chips are exposed in a rectangular batch called a reticle. The reticle mask has repeated patterns across it, and it is then exposed repeatedly across the wafer. So either they have to make a reticle mask the full size of the wafer, which sounds expensive, or they somehow have to precisely align reticle exposures so that the joined edges form valid circuits.