Ok. Since I was a tanker in the Army. Ill try to explain it as a tanker and as a gamer. Are modern MBTs pretty much impervious to small arms fire (i.e. rifles, smgs, lmgs, etc)? Yes. Is the armor on most MBTs effective against other tanks. Yes, but to a certain extent. All tanks have a few weak points (and some games actually have them). The sides and rear. Hit any tank in the tracks and congrats, you went from a 70 ton avatar of war to a 70 ton gun emplacement. Hit a tank in the rear and you damage the engine (see gun emplacement) or batteries. Electrical systems die and you now have a very very very slow moving turret with optical sights that cant really hit things at the range the tank was designed to shoot at. Infantry is a tankers curse and favorite target. Favorite cause well a 120mm HEAT round will turn a squad into chunks of meat, curse because if they start climbing on you then well you're pretty much fucked. Now, someone noted that missiles have been built to kill tanks yes. But now alot of tanks have counters to the missiles. For example reactive armor, or any active kill system. (see russian arena) To put something this damn complicated in a game will kill the fun of the game. Now granted I always go for the tank and try to do as much damage as possible in a quick amount of time because virtual tanks, just like the real ones, are really good at attracting attention. The boom kind of attention.