Why non-mining validators still matter (even if miners orph…

Why non-mining validators still matter (even if miners orphan single invalid blocks)
- Define the payoff surface: Miners are rational relative to what the economy accepts. Independent full nodes define “valid” for the economy. Remove them (SPV-only world), and a majority-hash cartel can rationally ship new rules and SPV clients will just follow the longest chain.
- Prevent capture/collusion: If regulation or a cartel pushes altered rules, validators that refuse those blocks make mined rewards hard to monetize. That’s a credible constraint on miners’ behavior.
- Self-verification and censorship resistance: Most users/services source and verify transactions via public full nodes, not direct miner peering. A wide validating network increases inclusion paths and lets users verify without trusting miners or gateways.