Ok, now I understand at least one issue with filteroors. They don't understand that this problem is dynamic.
They think like statists do. I don't want X, so I ban X.
That's not how the world works. You have to ask a different questions - I don't want X, if I ban X, what would people that were doing X do next? And if it is worse than X, the rational thing is - don't ban X, I don't want them to do the worse thing!
I don't want spam, but since it is in principle not possible to ban it in a permissionless financial network, since spam can always be embedded in the transactions, we want the spam in the least disturbing way. I.e. op_return.
Not understanding this is low IQ thinking.