If a decentralised system is to stay decentralised, it needs to consider spammy bad actors.
What if I own a server and connect it to an ISP under an agreement where the ISP is accountable for clearly malicious behavior coming from its connection (regardless of origin)?
Then, that ISP requires the same agreement from me, and everyone connecting to that ISP, and on down the chain.
Wouldn't we all be very active in policing bad actors in the networks we manage?