I don't know about your specific experience, but sometimes picking off snipers is difficult if they doing a good job of covering each other. My biggest complaint is that a tank shell to the knee caps of a sniper will usually only do a moderate amount of damage, yet a sniper can take out mobile artilley without ever being seen. If it were me.. after 21 minutes of problems with snipers, I'd be going after them myself. Usually if a team has an abnormal amount of snipers then their base is probably not properly defended, so (if you have vehicles) a good tank rush either destroys their base or gets the snipers moving and off your back.

Personally, I just don't worry about it, but I don't tend to run into the problem as often as it sounds like you do. I simply accept the fact that people can't become experienced without playing and making mistakes. The multiplayer practice is useless for anything other than learning how to aim and drive.