No. The purpose of heavily armored units is not light recon and scouting. It's meant to be the backbone of the battle and as such needs to be on the front lines. The vehicles which are for capturing flags are called transports - fast vehicles suitable to getting in enemy territory and providing enough threat with a decent driver and gunner to hold back light resistance, which would be the typical 1 or 2 flag defenders not on the front. A tank is a heavily armored behemoth there to do just as you say - frag people, as well as its top priority being to stop enemy vehicles. An APC offers some more options when it comes to troop transport, but its main function is also to fight, its advantage being in its higher top speed than a tank (though lower acceleration) can allow it to get from point A to B quicker. The APC also performs very well against infantry.I don't know how many of you guys notice this, but what's up with these tank/APC whores who just sit around, doing nothing for the team? The pick a nice cozy spot and just start killing enemies. Sure, that's all fine and good when your team has all the flags, but what about getting a flag?
Since you're using Karkand as an example, all the flags should be captured by at least 2 people in a TRANSPORT - for US, this would mean blitzing by the initial MEC hotel force to take square, or if square is too unsafe, take suburbs (and possibly infiltrate further). When you go taking flags with tanks, not only do you take the tank out of its most effective environment (fragging and earning tickets for your TEAM), you're putting it out on its own with no infantry support, vulnerable to people spawning on it with C4 while it tries to capture the flag, or enemy MEC vehicles detouring to the tank that's trying to capture the flag for a first shot advantage (you can be guaranteed if the MEC commander isn't a complete moron he'll be spotting the lone tank trying to capture one of their flags).
Armor works hand in hand alongside infantry to push back the enemy and capture flags by brute force, not stealth and evasiveness, which is what transport is for. Flags are nice for counters, but the games tend to rely more on who's getting more kills, and a tank who is killing en masse for your team is making a significant contribution for your team.