Very interesting! I am a qualified no.
First there's no single "federated timeline". It's a Mastodon feature that lets you eavesdrop on the conversations of other people on your instance.
As such, it's a place for discovery. It's explicitly stuff that you personally haven't subscribed to (yet). It's the feed of posts that aren't interesting to you.
All that said, it is nice for people to be able to explore there, and bulk automated posts probably fill it up and make discovery difficult. So it's probably polite for bots with a lot of repetitive posts to use "follower only" or "unlisted".