I think we are talking about entirely different classes of hardware.
The z16 is designed to run applications that cannot fail. In some cases, the datacenter is expressly built around these systems to accommodate their unique capabilities.
The Graviton line is designed to run as many applications per unit of volume and power possible for a multi-tenant, hyperscale ecosystem.
If a CPU core goes bad on a Graviton chip, you would likely need to redeploy your EC2 instance (or it would be done for you automatically). This would almost certainly have some downtime for your application. In the z16, if an entire CPU goes out, you hypothetically won't drop a single transaction if you followed IBM's guidance.
