> It turns node runners into network police It doesn't turn them into "network police" because they aren't policing "the network" (other people's computers) but only their own. I run spam filters because I don't want spam in *my* mempool. If other people want it, great, their computer is *their* responsibility. > constantly define and redefine what constitutes spam It doesn't constantly need redefinition. Spam is a transaction on the blockchain containing data such as literature, pictures, audio, or video. A tx on the blockchain is not spam if, in as few bytes as possible, it does one of only two things, and nothing else: (1) transfers value on L1 or (2) sweeps funds from an HTLC created while trying to transfer value on an L2. By "value" I mean the "value" field in L1 BTC utxos, and by "transferring" it I mean reducing the amount in that field in the sender's utxos and increasing it in the recipient's utxos. > Data-embedding techniques will simply evolve to bypass the latest filters And filters will simply evolve to neutralize the latest bypass. They cannot withdraw this race if the filtered are more diligent than the spammers. > [What if they] make their transactions technically indistinguishable from "normal" financial ones Then we win, because data which is technically indecipherable cannot be used in a metaprotocol. The spammers lose if their software clients cannot automatically decipher the spam. If the spammers develop some technique for embedding spam that can be automatically deciphered, we add that method to our filters, and now they cannot use that technique in the filtering mempools. If they make a two-stage technique where they have to publish a deciphering key, then they either have to publish that key on chain -- which allows us to detect and filter it -- or they have to publish it off-chain, which is precisely what we want: now their protocol requires an off-chain database, and all of their incentives call for using that database to store more and more data.