It does.It says ...
It's not a "rule" at all - merely guidance/recommendation in an 'informative' appendix of BS7671.It is not a hard and fixed rule, ...
Exactly.and the load from an oven under 3 kW will be a lot less than a washer/drier or drier on the drying cycle. Due to the time it draws the high current for.
That's certainly true of a DW and WM, since they only heat small volumes of water and that doesn't take very long at all. I'm less sure about an oven, although it obviously will not draw current anything like 'continuously'.The Oven, Dish Washer, Washing machine (without drier) are all around the same load and time, they may use 3 kW to get up to temperature, but not for long, ...
I'm not sure what makes you think that. Indeed, 'comprehensive space heating' (per the guidance in Appendix of BS7671 you are quoting) probably did not exist in those days - one 'electric fire' probably being all that most homes had!.... It does seem strange as the electric space heating was the whole reason why the ring final came into existence ...
As with so many things, it really comes down to the need to apply common sense!
Kind Regards, John