At least with soviet players, its not what units you should make (obviously you should make rhinos), but how you control your units (rhinos)
Many not so experienced players can make loads of rhinos, but have no idea how use them.
A decent battle fortress user knows how to run away behind other units or base defenses when hes chased by rhinos.
So obviously you shouldn't just go chase a battle fortress with rhinos in those situations. If you don't have an iron curtain. you need to overwhelm allied players army if you want to kill it, you need to be absolutely sure you will overrun him if you want to attack the army. so just keep making tanks, and overwhelm allied when you know you can.
And why would you want to attack the opponents army anyways? It's RTS. Economy means everything. Attack his economy, not his army.