I think this is for avoiding a map with just only vote (5 stars) go direct to top with a average of 5 stars...
The average systems often seems "stupid", specially with just a few votes... If I have two cars and you don't have none, the average says we have one car each other... But the more votes, the more representative... If you want to compare to maps, them should have the same (or near) number of votes.
Rate systems can be confused if you can't search what you want. In a ideal system you can search for example just maps with more than x votes (popular maps), maps with few votes or unrated (new maps)... And is more confusing when you show in the same list maps with lots of votes and maps with a few votes in the same list, and you try to order it by average.
Some people try to create formulas that allows to put toghether people like you (zero cars) and me (two cars). And this is because it seems weird. It's not logical, is just an average. And If I have 9 cars, and you have 1, you will have 5 cars. The most diference betwen two examples, the more ilogical it seems. I don't really think you can compare the rating of two tracks with diferent number of votes in a logical and representative way in order to know wich is on top and wich is down. Try the formula you want, and the final result will seem stupid and ilogical.
I think is better tu use the simple fórmula: X stars/X voters= rating. This way rating number is telling to you something logical you can easily understand without burning your brain with strange abstract formulas. But don't try to compare maps with 100 votes with maps with 2 votes by the average. This is just stupid, with the formula you want.
Anyway, the magic formula that can compare potatos with bananas is the same for everybody.... XD