I think it's because Battlefield is a lot more tactical than running around quickscoping people, and BF fans get upset when you compare their tactical game with people complaining about Noob Tubes, quickscopes, hardscopes, no scopes, camping, wtc.
Then again I haven't owned a BF game since BF2, so maybe they do complain about all that stuff nowadays...
Then again I haven't owned a BF game since BF2, so maybe they do complain about all that stuff nowadays...