I agree with you but I think the technical capability intersects with politics here because anyone is able to make new stuff out of old data. That’s not the same as Google carrying it through to another Google product. I’m not aware of the FOAF/XFN stuff but it’s also different if that isn’t the entire graph perfectly preserved, easily queryable by everyone involved.
When developers feel empowered to revive products or fork them, I think that eventually seeps into communities. That it’s another way of doing things. It doesn’t happen overnight but this energy exists in the Atmosphere. Maybe loss of Bluesky is not survivable culturally at the moment, but maybe it will be in a few years as Atmosphere grows and matures.