I understand why you say those things have big differences, but when one tries to articulate those differences in a legal and policy framework that allows the things one wants but not the things one doesn’t want, I think the lines separating the differences becomes grayer and grayer until they are in danger of disappearing altogether. I personally am in support of tooling to migrate communities, policies that allow it under appropriate circumstances, and a culture that embraces it “when necessary”. The details of appropriateness and necessity are complicated, but for me there’s a bright line well short of “ask everyone before preserving anything” where preservation/migration projects are allowable.

But I don’t have a lot more to say about this in the absence of a concrete real world context. If the fediverse continues to thrive, I’m sure we’ll see those contexts arise at some point and can discuss how people are viewing the situation and whether they’re able to encode those views into rules and enforce them. It will be interesting to see develop.

Edit: Your edit came in as my post was landing. I couldn’t disagree more that archiving should be opt-in. The most important preservation is the preservation of content that someone wants to destroy. And bad actors cannot be avoided, rather it’s bad actions that must be limited… through the consistent application of good policy equally to people whose intent you trust and people whose intent you distrust.