2nd one first - I owe you an abject apology.So where have i said anything that says i dont know what a ring is or how to wire up a FCU or how it works.
I read your post as saying you thought than an FCU directly on the ring would blow if the current in the ring exceeded 13A.
No idea why - what you wrote was quite clear. I really am very sorry.
As for the ring, questioning the accepted concept of one is nonsense. It's either a ring or it is not - you might as well say that you want to challenge the accepted concept of what a square is. If you add a loop of cable at one of the sockets on the ring you have not extended it, you have turned it into something which is not a ring, and that is immutable topological fact, not an alternative concept of what a ring is.