Sometimes grandmaster but frequently diamond player here that also built my own company where I frequently coded 12+ hours a day. I disagree with you completely. I was also significantly more exhausted from a long session of league then I was from a long session of developing one of my sites. You are always on for 30 minutes straight and near the end it’s almost non stop team fighting and positioning with micro decisions being made every few seconds versus coding where my mind will wander until I snap it back to focus.