The trend is away from federated services.
Email, the Web, and Usenet were all created before the modal HN user was born. Of those three, Usenet is basically not a going concern (beyond paid binary newsgroups for piracy, honestly). The Web is increasingly siloed off. What federation there is exists largely thanks to commercial CDNs and peering, not user-facing federation that benefits user freedom.
I'm not sure IRC was ever motivated as a federated model. It's true users can run an IRC server, but the main advantage of IRS compared to previous attempts at multi-user chatting (whether asynchronous like BBSes or synchronous like early chat platforms) was that it allowed confederation of servers into server networks. But also my impression is certainly that IRC is moribund with many long-time users having pivoted to Slack or Discord, both centralized.
Rather, where federation is growing, it's largely recent, fringe experiments. That's not necessarily a bad thing, mind you, let a thousand flowers bloom. Mastodon might end up working out for some definition of working out. I doubt PeerTube will.
But in any case, it's more accurate to say that some of the early internet was built on decentralized platforms, some of which were federated, and that recently some tech enthusiasts have recently written some interesting, maybe promising federated platforms. There is definitely not a trend toward federation.