Like most design rules, they're there to safeguard you. They prevent you from making any major mistakes that can make a space feel uncomfortable (figuratively and literally) or in any way less livable. But following them too closely can also prevent you from adding the sort of tension interior design often requires to be truly remarkable.
Heard of the 60-30-10 color rule before? It’s an approach where you use a dominant shade in 60 per cent of your space, a secondary color in 30 per cent, and the last 10 per cent is for accents. It's the science behind the art, if you will, and helps avoid overwhelming a room with color.