GH:
My point precisely. When the “bein hazmanim” concept developed, the halachos of Chol Hamoed were long in place. In fact, that Mishna is not the source for the halacha. It is just another reminder of the severity of these halachos. It can be argued that the relaxation during leisure time can become part of the mitzvah. We find that HKB”H also allowed רווח בין פרשה לפרשה, sort of a breather for Moshe Rabbeinu. Our sleep can also be a mitzvah if it invigorates us to be able to fulfill mitzvos. Staying up all night learning (sleep deprivation) and fasting have their places. But halacha keeps these to a minimum, as the Torah recognizes these as needs that facilitate our doing mitzvos. But to use this “free time” to experience חירות מן המצוות is absurd.