Thinking that having dedicated independent circuits is madness sounds like Stockholm syndrome. The point being a single faulty appliance won't knock out the lights and sockets to half the house simultaneously (a common occurrence during a fault in the UK, especially the RCD). It's also quite convenient to switch off a single appliance for service. Yes British sockets are all switched but not necessarily in a convenient location.

A software analogy would be running all your services on separate VMs, as opposed to running them all on a single server which could go down at once.

Brits don't even put outlets in the bathroom, minus a current-limited transformer-isolated one for an electric razor.