I think this depends entirely on the organization and size of the product. If you have one "squad" that owns the product top-to-bottom ("squad" being defined h

I think this depends entirely on the organization and size of the product. If you have one "squad" that owns the product top-to-bottom ("squad" being defined here as a team with daily discussion and syncing of progress) then I think the architect aspect is decentralized across everyone. But once there's more than one "squad" that each own a separate chunk of the overall product and the work of these squads overlap even a little bit, then there must be one individual who is enforcing a confluence of design in that overlapped region.