the point of idle maps are to gain items for crafting to get hats mostly. http://www.tf2wiki.net/wiki/Hat "the game rolls an 84-sided die every 4 hours, 17 minutes, and 10 seconds (15,430 seconds in total). A hat is given on a roll of 1, 2, or 3 (3.5714% chance)." Most other servers will boot you out if you're idle.