The summary.
THE TECHNOLOGY PROVIDES A RECORD NO SINGLE PARTY CONTROLS
Verifiable history, and rules executed without an intermediary. It does not provide truth about anything outside itself, reversibility, privacy, or ordinary database performance.
ASK OF EVERY PROPOSAL WHETHER IT REQUIRES THE ABSENCE OF A TRUSTED PARTY
If one exists and is acceptable, a database is simpler, faster, cheaper and correctable. That is the honest answer to most proposals.
THE ORACLE PROBLEM ENDS TRUSTLESSNESS AT THE BOUNDARY
Anything depending on external facts depends on whoever supplies them — which reintroduces exactly the trusted party the design was avoiding.
A TRANSACTION IS IRREVERSIBLE ONCE SETTLED
Sending to the wrong address loses the funds permanently, with no recourse.
IMPROVING THROUGHPUT USUALLY COSTS DECENTRALISATION
Ask what was given up to achieve any performance claim, and examine who actually produces blocks — many nodes with few producers is less decentralised than it appears.
BRIDGES BETWEEN NETWORKS HAVE BEEN THE LARGEST SOURCE OF LOSSES IN THE SECTOR
STORE FINGERPRINTS ON A LEDGER AND THE DATA ELSEWHERE
Every node stores everything forever, which makes it extraordinarily expensive per byte.
