Okay, now that I'm less tired, a more salient point:
Opt-out is not "you haven't consented," opt-out is "we have a situation where there is generally consent and we are giving you the ability to _revoke_ that consent."
For instance, if I'm setting up a mastodon server, the fediverse has a _generally granted consent_ for me to do the things a normal mastodon server does, but they also provide a(n imperfect, more on that some other time) mechanism of consent _revocation_: blocking.
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We also lack fine-grained controls around these things. We don't have a way to say "I never want my post to show up in Lemmy." We don't even have a way to say "I don't want my post to ever show up on the blocked server."
Your solution if you don't want to consent to these things is _limited federation_. Not authorized fetch, but actually allowlisting the servers you talk to.
Because we don't have a way to say/enforce these, your option if you aren't comfortable is to not participate.
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