Pleas note, the only place in BS7671 where requirements for circuits to be provided with RCD protection is to be found, is in the section for special locations.
Such circuits are those of a location containing a bath or shower, circuits supplying socket-outlets in Agricultural/Horticultural Installations, etc.
Yes it may well be that the easiest or most cost effective solution will be to provide RCD protection for socket-outlet circuits, rather than individual socket-outlets, but there is no requirement to do so.
It should also be considered that some circumstances, providing RCD protection for socket-outlet circuits can cause nuisance tripping, and could actually be a non-compliance.