3 reasons why this is a BAD idea:
  1. The sub will instantly be filled by dozens of ads for Ordinals and other BRC-20 crap tokens -> will damage signal/noise ratio even more
  2. Some of the listings will be illegal stuff, can't prevent it -> possible legal troubles for SN and dev team
  3. Crypto markets and Nostr marketplaces already exist -> no need to compete with that, and zero legitimacy for SN to go in this direction ("News",remember).
I would add that the fact that this idea could be debated is yet another proof that SN lacks a vision for the future. As long as there is no clear ambition/vision expressed (I would dare to say "roadmap", or at least a plan), people will suggest exotic (and bad) ideas.