Honestly I think it should be L56+. Until you've unlocked all the maps, you're not actually exposed enough to what's out there (which has a serious impact on how you rate things
knyte, access to almost every map doesnt change the quality of rates. It neither guarantees that players played various maps or have a better understanding for strategic values nor that they fully understand the map making process, the effort which was put into it and the resulting quality of the map.
It will only lead to a significant decrease of rates and reviews for new upcoming maps.
Why not a mix of them all? 15 days since account creation, at least 25 multiplayer games and level 10.
First point is useless, as long as you will probably need 15 days to level up your new alts!^^ The time delay will still not prevent manipulating the results. The other points might be useful to hinder trolls like
anonym, but it will also keep out players like Nathan, who made great reviews for almost every map.
Until this dont become common praxis, it will be best fizzer simply bans the troll and undo the rates.