|> The ability to rate a map is only available to players who have actually played a game to completion on the map. This helps prevent drive-by ratings, where someone looks at a map for a couple seconds and makes up their mind without even trying it. By not allowing drive-by ratings, the hope is that the map’s average rating will be more influenced by the people who like that type of map.
While technically possible, it would take extra work to automatically determine if people ever played a game on (the most current version of!) a map and then allow them to rate. Besides, the need for such a function rapidly decreases over time (assuming people rate maps they still wanted to rate after their next game on it).