[Packaging separate dies, each made on distinct process] is cheaper than [use 1 process that is sub-optimal for big part(s) of the chip].
Or: advanced IC packaging is cheaper than advanced semiconductor manufacturing.
Still surprising this works for a <$1 chip. But makes sense considering what a new semiconductor fab costs nowadays.
[Packaging separate dies, each made on distinct process] is cheaper than [use 1 process that is sub-optimal for big part(s) of the chip].
Or: advanced IC packaging is cheaper than advanced semiconductor manufacturing.
Still surprising this works for a <$1 chip. But makes sense considering what a new semiconductor fab costs nowadays.