Someone please correct me if I'm wrong, but my understanding is the first time you search a @community@server your home Lemmy instance discovers it, and you will see future posts but not posts from before the discovery. It only takes one person in a Lemmy instance to discover a community for the whole instance to benefit. So if I was on the same Lemmy server as you and searched /discovered the community a week before, you would see 7 days of posts.
I think funny@server1 and funny@server2 are two separate communities which could be a good thing but also confusing to new users.
I get the essence of that quote but I feel it falls apart under any scrutiny. Drunk driving laws are widely agreed to be a good idea but that would fall until the category of sacrificing liberty.