Well if you really want to get into it ...
No – wartime rationing made certain methods habitual, but it wasn't solely responsible for creating it.
The Tudors used an abundance of cooking fat – but there was a rich/poor divide in using it. Fat, in Britain, has always been expensive, unlike in Europe where there was an abundance of olive (and other) oils. Fuel to roast food was also more costly.
Less meat was also available in Britain, as opposed to Europe. The meats we saw most of were mutton, brisket and offal – stewing and boiling made these meats more palatable.
Britain was also industrialised before other European countries, and one-pot meals and stews were more convenient and practical for working hours and crowded, urbanised households.
However, when other cooking methods and culinary options could have filtered into the country, that's when we were hit with both rationing and post-war austerity. And this is why the habits have really taken hold.