NIP 4 still handles the spam angle with a possible wot filtering without payments. This makes it usable. Usability comes first. Encryption is still hiding the content, and we can NOT do better, at the moment because _someone_ must pay for DMs to be more private, that's just the reality. I funded a NIP17 PR to be included in NDK. It was merged, and then I realized the shortcomings so couldn't actually implement it in SatShoot, and I was not happy about that. I agree NIP17 is the way short term, WITH payments. Perhaps MLS later, or signal protocol. But without paying users it's hopeless in my opinion so I am tackling that problem first. Beating the drum about DMs doesn't get you anywhere, and no, it is not an easy problem.