Interesting article. So what they're saying is that even if you don't have the MTHFR mutation, you can experience the same sorts of problems due to magnesium deficiency, which is due to candida, alcohol, cigarettes, car exhaust, not to mention a magnesium deficient diet, such as a processed food diet.
This would explain the mechanism behind CF i.e. "chronic fatigue", which people confuse with ME/CFS.
In addition, magnesium deficiency can cause restless legs which will cause unrefreshing sleep or insomnia, making you even more exhausted.