I think the author simultaneously gets and misses this with this article. The Sri Lanka example is really a perfect example of what happens when the consequences in a monetary system stop being enforced and how it drives people to lose trust in that system. You could maybe build a cryptocurrency with enough regulation and enough force of consequences that you could replace other financial systems, but at that point it would simply be a more globalised version of our current banking system.
I think trust is easier understood with the “smart” contracts in the form of how we deal with landownership around the world. In countries with stable low-corruption governments you don’t need “smart” contracts because you can trust the system to uphold your rights, but, in countries with a high level of instability or corruption you can’t use your “smart” contract because nobody is going to enforce your right.