“An opt-out setting that quietly ships settings data off-device is exactly the sort of thing that adds to administrators’ workloads rather than lightening them.”
Backup goes on by default, ships your settings to Microsoft’s cloud, and you have to hunt for the switch to turn it off. Except in the EU, where the Digital Markets Act makes that illegal, so there it stays opt-in. That exception tells you Microsoft knows exactly what it is doing. If the default were actually good for users, they would not have to be legally forced to offer the choice.