The idea has merit, in theory -- but in practice, in the vast majority of cases, having a trusted regulator managing the system, who can proactively step in to block or unwind suspicious activity, turns out to be vastly preferable to the "code is law" status quo of most blockchain implementations. Not to mention most potential applications really need a mechanism for transactions to clear in seconds, rather than minutes to days, and it'd be preferable if they didn't need to boil the oceans dry in the process of doing so.

If I was really reaching, I could maybe imagine a valid use case for say, a hypothetical, federated open source game that needed to have a trusted way for every node to validate the creation and trading of loot and items, that could serve as a layer of protection against cheating nodes duping items, for instance. But that's insanely niche, and for nearly every other use case a database held by a trusted entity is faster, simpler, safer, more efficient, and easier to manage.