I had exactly the same experience of FedWiki. Couldn’t really figure out how/why to use it.
Reading about it (e.g. https://commonplace.doubleloop.net/a-platform-designed-for-collaboration-federated-wiki and https://commonplace.doubleloop.net/choral-explanations-and-oer-a-summary-of-thinking-to-date) helped a bit with the why. Not so much the how.
Then I played around with it again recently (thanks @email@example.com) and it suddenly clicked. Bit of a galaxy brain moment.
That said I probably still won’t use as a daily driver for now (Im wedded to my current paradigm) but can see now why I would.