Pretty much all distributed databases trade off ACID for speed, it's a fundamental issue with database design.
If you've got 20 database servers, potentially on the other side of the planet from each other, if you were to be ACID compliant throughout the cluster, each write commit would be delayed up to 500ms or more.
If you're running a pair of servers in the same room, as is normally the case with a traditional "active-active" database cluster, a network delay of 1ms often isn't a significant impact.
If you've got 20 database servers, potentially on the other side of the planet from each other, if you were to be ACID compliant throughout the cluster, each write commit would be delayed up to 500ms or more.
If you're running a pair of servers in the same room, as is normally the case with a traditional "active-active" database cluster, a network delay of 1ms often isn't a significant impact.