The real reason p=none persists is because people would rather err on the side of email being delivered that is actually junk than having a miss of legitimate mail. (This also the reason for so many soft failure entries in SPF records.)
This is true. Here’s a cautionary tale to that end. My org’s IT recently introduced, without input, an ai filtering tool to automatically filter junk email. It apparently worked too well. In an ironic twist of fate, it filtered a raft of emails (across multiple domains, including tickets and account reps!) to IT from an important vendor about contract renewal into junk that ultimately resulted in leaving the vendor no choice but to suspend service until the bill was paid (they waited until the very large bill was over two months past due to do this, to their credit).
When I learned about this during the post-mortem I was incensed, to say the least. Email mgmt is part of a professional’s job, for better or worse. Accountability for that doesn’t suddenly evaporate because of a scenario like this. I don’t practice zero inbox for fun. I do it for my sanity and effectiveness. Technology can’t magically solve every problem.
