You have to realise that the UK (and Republic of Ireland, and a few other countries) use fused plugs.
So we can have a large number of sockets off a 32A breaker, in fact our regulations don't limit the number, and then each appliance will have its own fuse, typically 3A, 5A or 13A, depending on what it needs.
Thus fault handling is usually the appliance fuse going, for example if the flex is damaged, but if the fixed wiring has a fault or someone manages to load enough sockets up then the breaker is there to clear it.
Because of this we typically will wire a whole floor of a house on one ring circuit with the two ends going back to the same breaker, and to make the cable cost lower we use 2.5mm cable (about 13 AWG, instead of 4mm, about 11 AWG, in most cases). This also has the advantage that our CPC (earth/ground wire) has no single point of failure, typically if the ring opens on the CPC the socket is still earthed by one leg, as are all others.
Now using 4mm you can run the same sort of thing (lots of 13A sockets on a 32A breaker) but you have a much shorter length before voltage drop becomes a limit, and an open CPC leaves the remaining sockets without ground/earth protection.
So it really is just for our general purpose socket outlets - for large fixed loads like cookers, showers, water heaters, etc, we put them on their own breaker as a radial circuit.
