Considering that XMPP federation has been turned off for some time now, this really only hurts users using XMPP clients.

I was wondering why my friends with non-Google Jabber IDs were never showing up as online, and one day figured out federation was turned off.

This is as if a few months ago your email provider silently discarded emails to and from other domains, and just today abandoned SMTP and IMAP.

The true failure happened way back when federation was abandoned, not today.