Well, i think a ranking system can easily split the community....one side loves/wants it, the other side hates it. Count me to the second side.
However, i think generally refuse a ranking system isn't the way to go. Also i think it's indiscutable to have a permanent ranking system.
I guess the best way is to find an optional way through all this. Server owners may decide if they enable rankings or not. Mission makers may decide if they build in ranking options into theyr mission (rewards for kills, goodies they can get) and players should be able to choose by them self if they want their stats stored or not.
At first it looks as this would end up with a mess, but i think it will balance itself. Some serverowners might decide to deactivate ranking, therefor no ranks and stats are shown/stored. Some Missionmakers might decide to not restrict things for lower skilled (whatever that means) players.
I guess at the end all will benefit from an open system where everyone may choose by himself. If you like a ranking system, enable it at your side, look for ranked servers and for ranked missions. If you dislike it, then just keep away from ranked servers.
The problem about storing the ranks and stats is then a technically problem. I'm no IT specialist so i wont give any comments about it besides this one: right now it is already possible to have a squad.xml....why not developing something based on this?