This seems to be the heart of our disagreement. You say spam doesn't present a threat similar to a DoS vector; I say they both cause serious harm, but spam does so more subtly and more slowly. This article by Chris Guida outlines why: https://x.com/cguida6/status/1968117953871720463

As for why miners continue to mine spam, that is the golden goose problem: financial incentives can cause miners to slowly and subtly harm the goose, a knife cut at a time, to get the golden egg more quickly. But the goose may die by a thousand cuts. It is part of why I personally want to eliminate spam from my mempool and slow down blocks that contain it -- to provide a counter financial incentive so that miners will reconsider whether they should mine it or not. And it is also why I invite others to join me in the effort