Your points are well made. I have played as defender about 6 times against humans and I have yet to win. This is most likely due to a combination of factors, such as my inability to manage my troops, but is also an indication that defense against overwhelming numbers is a tough job. Like you, I am not complaining, just acknowledging that your observations are on the money.
I keep playing in defense, in the hopes that I will eventually get at least a draw.