Dumb question time: Aren't 95% of these use cases more easily implemented with a single central source of truth, possibly with distributed read-only replicas?

I think the blockchain innovation is amazing in the context where you have no trusted party. Bitcoin, for example. But almost all the other blockchain uses I see discussed have obvious central parties that people trust. E.g., Nasdaq already knows exactly how to run a very reliable registry at low computational cost and very low latency. [1]

So what cases actually benefit, and which ones are more (mis)applying the latest fashion?

[1] As an example, look at the LMAX architecture, which is orders of magnitude faster and cheaper to run than a distributed blockchain: http://martinfowler.com/articles/lmax.html