Nodes go down for many reasons such as power cut, hardware failure, maintenance.
The question is when, not if.
Many networks support 1 public key per node.
What happens then? The network stutters, the even chain grinds to a halt.
Recovery isn't simple, often depends on complex fallbacks & governance approvals.
For a system meant to run 24/7, that's a critical vulnerability.
Amadeus does it differently.