If you're just scrolling a bunch of random stuff, you might not care. But what if we want this to be like old Facebook, where you follow people you actually know? Am I going to miss wedding and birth announcements? Party invitations? Other important life updates from friends and family?
You could criticize the modern algorithmic feeds on platforms like Facebook for not showing some of these things as well, if they don't think it will engage you enough, but at least the post is there and available. When I ran into that issue between my 2 accounts, I looked for the post specifically, I had the ID... it simply wasn't available to me.
you could throw more money into the instance's tip jar to make it easier for them to decide to rehost a larger part of the data firehose - that may not be the entire reason they defederated from an instance but it may be part of it
you could move to another instance whose admin's choices are more in line with yours
That's news to me, as a Mastodon user. I just scroll my homeserver's default feed and get stuff from all over the internet.