Just make it, a seven rotation selection.
Have a list with all maps in comp.
then, have the player select 7/8 maps from the list that they are ok with playing.
The matchmaking doesnt suffer, and that "seasonal tilt" that players feel with maps gets negated.
For example, lets say you played bind too much, and at the moment hate the map, all you need to do is take it out of your selected maps.
For the dumbos that say to copy CSGO', Riot already said they aint doing it because it raises fraudulent players that are only good at one map, and it also increases queue times.