Roger Hayter explained :
I don't think that the existence of unswitched sockets is evidence
either way as to whether it is appropriate to routinely put in and take
out a plug from a live socket. The most common use is as a demountable
permanent connection to an appliance fed from a separate isolating
switch.

We don't routinely pull plugs out to switch things off and most loads
these days are relatively tiny anyway. Probably the most common larger
load to be constantly plugged in and out, is a vacuum cleaner. The
noise alone is enough to make you turn it off at the appliance before
unplugging. Most of the things we have plugged in, stay plugged in for
years.