I want to remind that we had a thread about Camels already years ago:
Though the thread went in different directions and I also don’t agree to 100 % of some of the statements I made there.
I think one Issue with camels is that they directly counter the strongest unit in the game AND can force the fight against them. This leads to the odd behaviour of all civs with meaningful camel bonusses having one exceptional tool against the biggest military powerspike in the game, the knight. Especially boni to the damage output (per investment) are critical to view as the common answer of knight civs is to add either monks or pikes both of which increase in effectiveness the slower camels áre capable in killing their destined target (knights). So if the camels kill knights 33 % faster the addition of the counters has way less impact in the battles cause you need more counters to effectively threaten the camels.
And from this perspective it makes perfect sense that hera specifically targets gurjaras and hindustani camels as they are the ones with the highest damage output vs the knights.