This was not idolatry, as depicted in Exodus - this was full blown state religion, held in the same esteem as Yahweh, and co-existing with worship of him. So much so that El later became identified with Yahweh, and now most people reading the Bible (including Jewish people, Christians, and Muslims) believe El is just another one of Yahweh's names, or maybe the name of one of his angels.
Plus the "not" part is the weakest part of historical study and archaeology. From this time we have about 1 page of text for every 10 years for the entire continent.
Imagine just how much is not recorded.
> this was full blown state religion, held in the same esteem as Yahweh, and co-existing with worship of him.
IIRC, I'm pretty sure there's also a lot about that in the Bible too (e.g Israelites worshiping other gods like Baal, people up to and including kings).