This is 2020. Microsoft is 40 years old. How many times should we repeats the same dumb mistakes over and over again until we collectively learn as an industry. This should have been stopped at the initial design phase. Clearly those in charge can’t make simple design decisions or haven’t learned from decades of mistakes.
Also migrating from client side to server side means an entirely new version of APIs. It means clients being broken and migration issues for customers. New servers with old clients means backwards compatibility, etc. It will take years unless Microsoft kills the old version aggressively which they won’t because they’re Microsoft. This is a problem that will live on for 5 years at least.