Well, the design of the plug also implies the design of the socket. I was born in the eighties, and I’ve never seen an electrical socket without a switch, except for the appliance socket used for the cooker, which is behind where you install the appliance - the switch is higher up, above the countertop where it is accessible.

Basic extension trailing sockets don’t, most of the time unless you buy a snazzy one. But it’s by no means a recent development.

Tom Scott has a video all about the UK power outlet plug and socket and it’s an engineering marvel. The switch is just one feature.