That's the real reason behind training at high altitude. It has nothing to do with lactic acid. Additionally, there's a problem with their theory. Your body's ability to convert lactic acid into energy is what drives your metabolic processes past the one minute mark. If you prematurely short-circuit it, your body does not use the proper amount of work with enzymatic conversion, lactic acid removal, and most important of all, your muscles are performing constant substandard levels. They can't perform at max level if you're handicapping them. So, you're really teaching your body how to perform a crappy level of work. Not a smart move.
If you live at altitude for several weeks, your body adapts to the shortage of oxygen. The most important adaptation for the endurance athlete is an increase in the number of red blood cells, which are produced in response to greater release of the hormone erythropoietin (EPO) by the kidneys. Red cells carry oxygen from your lungs to your muscles. More red cells means your blood can carry more oxygen, which partly makes up for the shortage of oxygen in the air. So to compete in an endurance event at altitude, you should live at altitude for several weeks before the event.