Because honestly cardio is rather unproductive in the first place compared to dieting. If you have to do it, Built has a great post in her blog about how to run HIIT cardio which is vastly superior to steady state with a few exceptions.
Steady state is most useful for burning off FFAs (free fatty acids) after doing HIIT OR when certain dietary conditions are met on very specific diets. The actual calories burned by steady state cardio is pretty negligible if you consider the time and effort spent on it.
