Because spam discourages users from running nodes I used the analogy of a Justin Bieber forum to highlight this: users want their server software to do the things they had in mind when they started running it. If "storing NFTs for use in altcoin marketplaces" is not one of those things, and yet other people are in fact using their server software to do that, then that is a technical problem. If they see no way to remedy the situation, it may very well discourage them from continuing to run that server. In the case of a Justin Bieber forum, I think its host *wants* to serve the text of posts about Justin Bieber *without* becoming a file storage system for NFTs. In the case of bitcoin, I think it varies more, but a large number of its node runners want to serve monetary transactions without becoming a file storage system for NFTs. If their server is filled with monetary transactions and very little spam, they will probably be delighted that their server software is working well and doing what they want. But the more spam there is on their server, they may become increasingly dissatisfied with the software, and stop running it. Just like a Justin Bieber server might just quit running the server if it gets filled with too much spam. On a related note, some node runners seem more willing to tolerate storing and relaying spam if it bets mined into blocks, and I suspect part of the reason for that is because "undoing" the spam-inclusion would require expending lots of hashpower, and it doesn't seem worth it. But in *your own mempool,* you can exclude most spam from that pretty easily, and spam filters help you do so. They help solve a technical problem in an effective way. It is therefore no surprise that when Core announced its intention to remove the large-op-return filter, many users switched to software that keeps it.