I do not play on easy, so I'm only guessing... Doesn't Kraxis get a lot of gold in the beginning? If he uses that to rush buildings and troops he can get seriously ahead.
As for the Altar player, what happened most likely is that they had the Treasury Vault and the Merchantcross Bazaar. And if the difficulty was one of the harder ones, their cash reserves would start high and grow exponentially.
Of course, on harder difficulties, seeing the AI with 1 000 total population or 30 000 income by turn 50 is no surprise. But it should not be so on easy, you are right.
As for the attack/defense, by turn 50, it's kinda low, if anything. I have two AAR posted on this forum. The values in those are: Turn 46, 19/39 (Krax based, assassin) Turn 50, 27/34 (Amarian based, warrior)