It is myth only it isn't. You see in the real wild west it wasn't a pure speed contest either. It was accuracy first and foremost. If you fail to hit your target well enough that he cannot hit you, it doesn't matter if you drew first. There is a quote from oen of the famous 'gunslingers' of the west. A real quote from, the real guy that pointed this out. Ray-sensei uses it occasionally, but for the life of me I can't remember the wording or the name of the guy.
Iai is the same way. It isn't about raw speed at the expense of everything else. It is about many things including timing, which is different from raw speed. Above all it is about effective cuts, because if your blade misses your opponent or fails to cut effectively you die. Period. There is little room for error. The other guy has a 30 inch razor blade too.
Now eventually you do reach a point where you can, if the situation demands it, draw very quickly and still deliver a well placed and timely cut. Getting to this point requires an enourmous amount of work at far slower speeds. It is absolutely vital to master the kihon of nukitsuke. Otherwise when you try to go fast it will simply be a sloppy mess that doesn't do you any good.
Don't think speed, think timing.
Charles Mahan
Iaido - Breaking down bad habits,
and building new ones.