Well, I think the description above is adequate, but for anyone who doesn't understand.
-TS has a native map-voting feature
-When you run AMXX, it doesn't work properly
-This plugin will stop people using the native voting
I can think of several reasons why you would want to do this
-you want to use voting that actually works (ie AMXX voting)
-you don't want your server to deviate from the map rotation
-you want to run 1 map 24/7 and don't want people to change it