I’d add a 4th - experience. Each client can offer a very different experience with access to the same content. While “protocol level” covers it at face value, the impact of those experiences might be transformational in and of itself.
Discussion
Right, but if it's a protocol level core superpower thing, we're talking about, the protocol level needs to enforce its core in some way across the whole, in whichever clients are built for whatever experiences along the way. I would argue the value exchange bit needs to be in that core, right alongside the content message bit. Otherwise different clients will own different ways of doing value exchange and if they have access to the content from one of the relays, perhaps in some manner unintended by the creator, etc, etc. If it is direct reader-creator with no intermediaries necessary across the whole network, that would be big.