I have found myself enjoying using a document database as the online store, and then using a 'big data solution' (we use Presto) for any analytics queries later.

Traditional migrations for relational databases are really painful. Document databases make this much easier, and if you've faced the operational pain of needing to migrate a large database (for example, it's so easy to accidentally lock an entire table in Postgres), you might be pretty compelled.

(That said, I think the pendulum is swinging back away from document databases. So you're in luck ;))