At one point I had 2 accounts. One was on my phone and one was on my laptop. I was in the process of moving to the one on my laptop (I know migration exists, but I'm weird and didn't want to do that). Anyway, I was on my phone and saw a post with my one account from some other federated server. When I went on my laptop I couldn't find it. I figured it might just need to propagate. I waited days... nothing. I've seen behavior like this a lot. You're not seeing a problem, because you can't know what you don't see.

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.