In my experience adding sugar directly helps in depleating the taste of the pot and would ultimately reduce the amount of sugar needed in a brownie mix, also by dissoliving it and cooking it will create a better flavor profile in the end because it has been boiled allowing for the flavor to reach its best. I take my cooking very seriously as well and I am a chef so I love to experiment haha, I have experimented alot and have found for some reason adding sugar helps dissapte the THC and emulsify it into the Butter , no clue why but your were dead on with your assumption of the oil .