Yeah it's a neat idea but I struggle to think of good use-cases for merge, other than toy datasets. If I'm working on a service that's sharding millions of users across dozens of DB instances a merge is going to be incomprehensible to understand and reason about conflicts.
> Yeah it's a neat idea but I struggle to think of good use-cases [...] If I'm working on a service [...]
I suspect that's simply not the use-case they're targeting. You're thinking of a database as simply the persistence component for your service, a means to an end. For you, the service/app/software is the thing you're trying to deliver. Where this looks useful is the cases where the data itself is the thing you're trying to deliver.