Please explain what specifically Manjaro is proposing to do that you classify as being "spied on." Don't handwave this away, actually answer the question.
"espionage: The act or process of learning secret information through clandestine means."
That is, the specific information does not matter; the fact that someone wants to keep it hidden (which is their stated preference), and someone else wants to collect it through clandestine means (which is how we could interpret a sneaky opt-out mechanism) is enough to define it as being spied on.
1. Your hardware specs are secret information? How many times you clicked on i3wm's settings panel is secret information? I mean OK, you might really want to keep the latter for yourself, sure, but calling it a secret information is reaching.
2. It very much matters what the specific information is. I too wouldn't want my Linux distro scanning my GMail inbox through their distro-bundled browser, of course. But how many times I started Kitty is something I don't quite enjoy being shared but I also wouldn't be outraged if it was.
Nuance matters, just doing an extremist takes does not help anyone.
I think a good example in support of your statement is the superfluous metrics wantonly spewed by, eg, Firefox. A cursory perusal of about:config will list many many default settings which are completely unnecessary for normal browser function, eg dom-battery, general telemetry, dubious DNS and dozens (maybe many dozens) of other better examples I've seen but don't immediately remember. The privacy holes here are mostly by design. Clearly more than necessary hardware info.
There are endless examples of data flowing where one wouldn't expect. Doesn't IP6 wrap the MAC address into the IP? This alone is pretty significant. It goes on and on, but I don't see this as an excuse to go full-nudist in a fit of futility with all data.
And another thing I frequently wonder: who benefits? I honestly don't see things functionally improving in a way that I can't live without as a result of all this telemetry. I don't see that many people clamoring for the kinds of improvements this telemetry is supposed to enable. I know technology does improve, but I just can't remember where things were so bad I needed to mass-email my dossier to the world. Generally, I just made a forum post or bug report.
Of course, that's your right. That's why I vet my software on a per-piece basis. It can be exhausting but I at least know that stuff that I'd be very not okay with being shared, is not in fact shared.
As said in another comment of mine posted just minutes ago -- practice shows that anonymous telemetry is the only viable way of getting some usage data. Almost nobody fills out surveys.
Do most software need those stats? I'd say they don't, but I worked on pieces of software that absolutely needed to know which parts are most used and which are almost not used because the extra features cluttered the UI and confused people, leading to less buys / subs.
I had trouble finding exactly what MDD collects, but my assumption is that it collects data about the hardware in use and what packages are installed, at a minimum.
Okay. So you can't explain how you are harmed by this data collection, and you have an opt-out mechanism you can use to disable it anyway. What are we complaining about?
I'm not saying I can't explain harm, I'm saying that the presence or absence of harm is orthogonal to the issue.
What I'm complaining about is the evasion of having to get informed consent to collect personal data. Opt-out is a way to try to cover your ass while at the same time being able to avoid asking for consent.
The argument for it is always the same: if we make it opt-in, then not enough people will opt in. Which is another way of saying "if people won't give us permission to collect data about them, then we need to stop asking permission."
Well, yeah. If opt-in doesn't lead to useful results, then you may as well not have the feature at all. But they want the feature, because it helps them improve their software. So, "collect data in a way that preserves as much privacy as possible by default, and provide a mechanism to opt-out entirely" is the least-bad option. It gives them the data they want, and it provides an opt-out mechanism for people who don't trust them with the collected data. It seems like the best compromise to me.
It's not really a compromise. It's devs declaring that they deserve access to this data regardless of what users want, and trying to make it less objectionable. It remains the case that this is a back door method of extracting data from users that they don't really want to give.
If users didn't mind giving it, then enough would say "yes" to the opt-in screen that it wouldn't matter. But they don't, so these devs are trying to impose the very thing users don't want as forcefully as they can get away with.
Please explain what specifically Manjaro is proposing to do that you classify as being "spied on." Don't handwave this away, actually answer the question.