@evan I would say no, if I'm understanding correctly. The browser should load b.example's content from b.example, not a copy from a.example . I'm mostly concerned about privacy here.

If a post or profile is *clearly* meant to be fully public to the world (and ideally it's hard for an author to do this by mistake), then I guess it's meant to be shared around, so sure, why not serve copies. Depending on the use case, there could be advantages to that.