Do good power cords have to be stiff?

I’ve also read from a few manufacturers that if your power cords seem too stiff, it might be that your equipment is too close to the wall, and there are lots of nasties in wall you don’t want too close to your gear...

Made me chuckle too. But when I moved my rack 6 inches out , my stiff cords became much easier to manage even though they were just as stiff.