Besides what's already said, there's also big value for the manufacturer to guarantee that the CPU runs ARM code. Even if it was price competitive to design an

Besides what's already said, there's also big value for the manufacturer to guarantee that the CPU runs ARM code. Even if it was price competitive to design an ARM-based CPU from scratch, and avoid all the patents, you'd want something (bug) compatible with the real thing to in order to run real world code.