Imo OG Kings were Good Guys, but They were Forced to Sacrifice People by Someone,
Only One who Refused, what happened to her? Disappeared at Sea.
At First, those Sacrifices were a heavy burden, but imagine their Children growing up to witness that, over time They will change & embrace it, and eventually it can't help but become a Sport for them, just a Hunt for their Amusement,
Nefertari turned out to have become a D.
And what do CDs tell their Children if They misbehave? D. will come & eat you,
This clearly indicates that if you don't follow these Traditions, you become Endangered by D.
So, I wouldn't say that D. is the one who ordered those Kings to make those Sacrifices,
But it's Someone who can Protect them from D. and if They don't Obey him, He won't Protect them from D.
This reminds me of Dorry's Words when He was Damaged & said that He didn't receive Divine Protection of Elbaph God,
It's also similar to when Pirates believe that They must leave Offerings at Sea, otherwise Sea God won't let them journey safely,
Same thing was seen with Shandians & many others,
Imo it doesn't matter what any Side is doing or were doing, there is clearly a "Crocodile" Figure here in this OP World,
Someone who is Influencing "Everyone" & Oda will blame him for all Events & Suffering & Change in People,