The early GA may not optimize production and commerce, however it gets you commerce and production *earlier*. In some situations it's better to have a little less commerce and production earlier than to optimize both of them later. It's not a "yes/no" question as to if the early GA works well or not... it depends on the situation.
As for bad-mouthing Carthage, I can point to a Sid level and Deity level game with pretty good finish dates where I've had an early (but not ultra-early like Portugal or England might with the Colossus, which is more beneficial in a 20k game imo) despotic GA. Also, if you really don't like the early GA, Carthage potentially lies in a position to get a Monarchy or Republic slingshot faster than probably anyone else (though admittedly Spain or India might become a Monarchy or Republic earlier due to a quicker revolution). Seafaring gives you more commerce from the get-go, and industrious allows quicker roads for more commerce earlier also.