They mention that miners use private mempools and will include transactions nonetheless as they have incentive of higher fees.(like they do it already, it's not an hypothetical thing)
So running nodes with filters only makes the network more split, and more centralized(miners will tend to run code that give them fatter fees overall). So it does not avoid spam in the blocks.
This is what I understood from their arguments.
Yes, spammers can still submit transactions directly to miners through private channels. But this isn’t free... it transforms spam from a low-cost, frictionless broadcast into a high-cost act of collusion. It requires coordination, trust, infrastructure, and, above all, higher fees. Filters work by raising the price of spam. That alone is victory.
Their argument is, at its core: “Because some will defect, all must submit.” That is slave morality.
If filtered nodes cause divergence, that’s not a failure... it’s a revelation. It exposes where sovereignty really lies: not in the many, but in the few who validate blocks. The real fear is not about spam, but about unmasking how centralized the network already is.
To say filtered nodes increase centralisation is to say: “Only total submission preserves unity.” But the filtered node refuses this. It says: “I choose what I propagate. I define my values.” It is not a passive conduit for garbage. It is a declaration of independence in a system quietly ruled by pools.
