So what Anthropic calls "telemetry" is really "telechangeability"? That's sits with me even less comfortably than did the idea that some features are only available with telemetry enabled.

That's just how big companies roll out software changes for software that auto-updates.

It's much preferable to be able to instantly fix it if the rollout of a new feature goes wrong than have everyone who installed the broken version bring stuck with problems until the company realizes the issue and rolls forwards with a fixed version.

https://martinfowler.com/articles/feature-toggles.html

Not necessarily. They probably have an integrated service that handles some telemetry and also feature flags, like Braze. They toggled the whole thing off based on telemetry settings. It's a bug I've made before too.