I would not compare it to SQL: I do not use SQL because there is no distinction of in-band and out-of-band data (your data and your commands/queries travel in the same channel, which causes a world of pain). But there are other database approaches that work very well. It's not a problem at all to serialize your data and store native Clojure data structures, even better than datomic does.

In other words, I disagree that Datomic is somehow natural or superior: it is "a" database, excellent for certain applications, not necessarily the best choice for every application.

In many use cases, database is where application state resides, hence a mutable database is a better fit.

There are Datomic flavored database in the Clojure ecosystem that is specifically design to address this point, e.g. Datalevin.