Doesn't matter how mong the AI is... It is equal mong. Unless someone comes up with a mathematical model which perfectly predicts the power and cost efficiency of units the only possible way to compare equal players is via the AI.
And the only possible way to compare good drivers is to put them in a car and roll from a mountain, certainly not against each other with their respective cars.
There is no less reliable method to compare anything anyhow then vs AI, even flat map void tests have more merit.
For instance I just ran a USF hard versus OKW standard AI and USF did indeed win, after about half an hour. Russia on the same settings dispatched the OKW in a 20 min rofl stomp.
Ai doesn't play like players.
Doesn't know current meta.
Doesn't micro like players.
Has access to ALL doctrines at ALL times.
Doesn't know how to do cap orders.
You literally could take a random person from the street, sit it behind your PC and tell it to play, you would receive equally valid results.