the way i have always seen it , is.....
the cab is moving air, the mic is capturing it, (air is energy, energy disperses quickly), .... and finaly the monitors in the CR, or the car, is another thing that deals with the movement of air,
rock guitar is generaly moving a whole lot of air, and if thres is too much space(still air) beetween the mic and the cab, it can seem to have less presure and impact as it is played, room mics are cool for some if not most tones, but when it comes down to tone, and punch , it seems to my ears, allot of it is right up there against the speakers, also,
you can add room to a close mic if you need it, but its a far more ambitions job to make the "take", a really fat, dry, chunky, signal from an "airy" source
my 7 cents