@gnusocialjp
My Japanese is poor and it may be insufficient to express my idea, so I am going to use English here. (Feel free to reply in Japanese)

The point you try to justify Firefox's telemetry is they being "harmless", because they do not contain personal information defined by the law.

However, we were discussing whether their act is good or not, and law is artificial so they are useless on discussing problems out of the legal system.

Nothing should be sent without permission if they are unnecessary (even if they are "beneficial"), because why send those in advance? (Assume they are not malicious) The developers always know better than me? It doesn't matter what they sent, or where they are sending to (even to "good" sites like fsf.org). So, regarding to your reply "例えば、リクエスト回数、検索回数、検索キーワード、パソコンやソフトの性能、バージョン情報などは、個人を特定できないので無害です。", do you think it is harmless if these information are sent to multiple sites, including known trackers? (Note: The multiple of 0 is always 0. Harmless is very different from little harm. )

Let's forget what the law tell us which things are private or personal, the telemetries may not be that "harmless" as you thought. Even if we assume it is just a harmless simple GET, it still tells the IP, User Agent that you set, and the time you made your request. Something is sent (just not "personal"). Moreover, a small fragment of information maybe harmless or useless for now, but when they are accumulated enough, they could tell some stories.

And then why the nude photo is harmful? (It's just an example) Because a nude photo alone (wearing mask) isn't enough dox you too, unless you are talking about laws again.

And look, "harmless" or not is different to different people and perspectives (the Firefox telemetry is harmful to me). On the Firefox topic, you tried to justify it from developer's perspective. Telemetry is always beneficial to developers (so they will always justify their actions), since they can know more about users and the performance. But to users, they aren't all fine with that. Developer have their freedom to make bad software or malware while telling their touching stories on how many nights they spent creating them (it takes time to build malware too), it doesn't mean the software is good or not.

If they are good people, they will just simply ask you for permission on first start, or provide options to truly disable those unnecessary features (Like GNU Octave). So both sides of people can choose. But Firefox does not. It even gives you a guide, pretending they can all be off. While most of them can be off, some of them still remains, but they never mention this. Even if we look from developers' perspective, we don't just develop all the time. We are users too, and we will face the consequence justifying or normalizing the bad intentions.

In the end, it's just about the lack of user's permission. Again I will use the nude photo as example, there's nothing wrong if someone ask me to send my nude photo and I say it's ok. However it's very different if they send my nude photo without asking my permission. (If you still insist on the nude photo being harmful, replace it with any other harmless thing)

Also here is another example on "beneficial features" declared by the developers.
> Starting with Firefox 91.1, Firefox now includes changes to fall back to direct connections when Firefox makes an important request (such as those for updates) via a proxy configuration that fails. Ensuring these requests are completed successfully helps us deliver the latest important updates and protections to our users.
https://web.archive.org/web/20220906172313/https://blog.mozilla.org/security/2021/10/25/securing-the-proxy-api-for-firefox-add-ons/