Medical research and consent doesn't work like this. If you track your patients without their consent, or you share their data without their explicit consent, you'll land in very hot water, which will cook you even before you can scream.

Similarly, a medical trial will take a very detailed consent before you can start.

Your opt-out telemetry is akin to your insurance sending you powered and Bluetooth enabled toothbrushes out of the blue to track you and threaten to cancel your insurance if you don't use that toothbrush and send data to them.

Or as a more extreme example, going through an important procedure not with the known and proven method but with an experimental one, because you didn't opt-out and nobody bothered to tell you this. In reality, you need to sign consent and waiver forms to accept experimental methods.

> I don't understand how you got from "there are scenarios where telemetry can get information that you cannot get by talking to users, here is one example" to "experimenting on non-consenting humans". What is the connection?

The connection is clear if your salary doesn't require you to not understand it.

Developers don't opt-in to telemetry? Maybe it's because they don't want to enable that telemetry, your experiments be damned.

Use proper engineering to demonstrate that your scripts work instead of demanding that users be your free software test team.

You said 'but we wouldn't have a lot of improvement without telemetry'. I am saying that we could have a lot of improvement in a lot of things if we wanted. We could have breakthroughs in medicine if we allowed human experimentation. The question is, where is that that line? Your argument doesn't address that, it just tries to justify something that people think it morally wrong by stating that we get use from it.