Well exactly.. a millennium after being ridden (3500BC) they were used as beasts of burden (2500BC).. rather the opposite of your claim.
The 3500 BCE date for horse ridding is speculative and poorly supported by evidence. I thought the language in the bit I pasted made that clear. "Horse being driven" means attached to chariots, not ridden.
Unless you want to date the industrial revolution to 30 BCE when Vitruvius described the aeolipile, we can talk about the evidence of these technologies impact in society. For chariots that would be 1700 BCE and horseback riding well into iron age ~1000 BCE.
"However, the most unequivocal early archaeological evidence of equines put to working use was of horses being driven. Chariot burials about 2500 BC present the most direct hard evidence of horses used as working animals. In ancient times chariot warfare was followed by the use of war horses as light and heavy cavalry."
Long discussion in History Exchange about dating the cave paintings mentioned in the wikipedia article above:
https://history.stackexchange.com/questions/68935/when-did-h...