Cosmos was originally created for hosting massive datasets internally within Microsoft. For example they use it for the OS telemetry sent in from customer machines, and raw data for threat intelligence. As part of Microsoft's move of everything hosted on-premise to their cloud, they decided to upon up Cosmos to other users of Azure. But the primary customer is and will likely always be Microsoft themselves. Which is probably why we see these breaking changes, it'll be in response to some internal ticket most likely.