There are 500 million posts on Twitter every day. Do you read them all? There are 2.8 million subreddits. Have you browsed them all?
Nobody subscribes to every twitter acct or every subreddit so nobody is expecting to have every single post delivered to them. The fediverse has a legitimate problem where ppl don't actually receive all the posts of accts they're subscribed to. It's silly to compare what the OP is complaining about to not being able to see every post on twitter/reddit.