Moderation and rules are extremely important. It will be necessary on decentralized platforms otherwise attackers will use the lack of moderation to desecrate such platforms and the authorities and the world will have reason to attack no matter the cost.
Decentralized platforms without moderation should be avoided in my opinion.
Moderation must be assigned randomly to qualified anonymous moderators. Their job must be done transparently. And there must be reward/punishment for good and bad moderation.
Such a system has been used successfully in Slashdot for over two decades. There the system random assigns moderators and meta moderators where you can build reputation by doing a good job from the community itself.