A "signed paper document" or a "treaty" is also meaningless without robust enforcement mechanisms.... or the instant it's in either side's interest to ignore.

That goes double for blockchains.

The keyword here is consensus. Using an append-only distributed public ledger to record your governance decisions (and be held accountable for them) is a lot like using a memory-safe language when programming. It induces non-negligible overhead, but prevents entire classes of opportunities for abuse.

The whole "blockchain-backed international treaty" example is admittedly a bit contrived though. It's kind of a "horseless carriage" thing - trying to explain to @markwkw that no "blockchain payments" would be necessary, by expanding on their mental model. (Maybe that's an unwise strategy, and I need to start just rudely dismissing people instead, but I'm not sure how that would help with comprehension)