CMBB v CMAK

[PoorOldSpike]

Pre-war American AT doctrine assumed that to stop an armoured attack you need simply throw loads of AT guns in its path.
This was fine provided you knew exactly where the attack was coming in, and provided you had ample notice to tow your guns into position, not always possible against a mobile attacking force which might strike in an unexpected sector.
Only tanks are mobile enough and well-protected enough to be able to quickly switch to the threatened sector to block an enemy armoured attack, so it naturally follows that the defending tanks must have a gun capable of stopping the enemy tanks.

Same applies when it's your armour that's attacking, the defender will move his armour to block you, so again it follows that your tanks should have a gun capable of taking them on..