> I have already admitted my obvious biases, but seriously - when you design such a trivially corruptible system, you can't call it a persistent database; it's at most a cache. It won't survive a system crash at all, it probably won't survive an application crash intact either. To call it persistent is laughable.

There are a number of use cases where in the event of a node failure it is better to rebuild from a replica or a log. Statistically, the RAM on another host is actually more reliable than local storage. Additionally, the database does have sync'ing primitives that allow for a variety of persistence strategies... just not the traditional ACID strategy.

In practice, there are lots of cases where the freedom to ignore transactional integrity is very handy, and yes, a cache would definitely be one of them.