Define "small subset." And how is it a failure of anything to use blastr and ensure that your notes are in as many relays as possible? That is far more decentralized than having my notes only on a couple of small and less reliable relays like your suggesting.
Discussion
nostr wasn't designed to have everyone use blastr to distribute their notes across every relay. not all relays want to host notes from everyone. this increases storage and resource costs for relay operators. it's not a problem now, but it becomes a problem if we hit 1M active users.
From a user perspective, blastr is insurance against finicky or unreliable relays and relay operators. It ensures redundancy of users' data so that even if many relays go down, your notes still exist somewhere and likely somewhere others will find them. Outbox model ensures your notes are findable wherever they are, even if on a single obscure relay. But Outbox does nothing to solve for redundancy of your data, from my understanding. With most users onboarding via mobile app clients using a small number of bootstrap relays, I don't see Outbox as being a magic bullet that instantly decentralizes user data and ensures it's redundancy. Blastr does. Maybe you see it as a crutch, but I see it as an extremely useful tool and if some relay operators don't want to host all that data, then all the more reason to blast it out to more redundant relays. Outbox sounds very useful, but it doesn't solve for some things users need.
I like the idea of doing this in order to find weaknesses, report issues, amd strengthen relays and clients as a whole. Doesn’t mean it’s how we should always use it to get proper distribution of our notes, but it’s early enough that those of us who want to can help kick more tires.
And then also make more blastrs to reduce centralization failures 🤷♂️
You're also discounting how many notes self-propogate. I've published the test results of my relay multiple times.
All notes on at least 3 major relays and 10 minor relays within 15 seconds, and it just expands from there.