So in a traditional DB you might have a DBA set up a reporting database so the operational one is not affected. Using Datomic the reporting service gets a datomic peer that has a copy of the DB in database without any extra DBA work and without affecting any web services. This also works nicely with batch jobs or in any situation where you don't want to have different services affect each others performance.

Its true that a lot more memory gets used, but it is relatively cheap - usually the biggest cost when hosting in the cloud being the vCPUs. But usually in Clojure/Datomic web application you don't need to put various cache services like Redis in front of your DB.

Thea assumption here is that the usual bottleneck for most information systems and business applications is reading and querying data.