I guess I just don’t get why you’d use this over Postgres if it has such a heritage of unreliable behavior and still doesn’t give you actual performance benefit

I guess I just don’t get why you’d use this over Postgres if it has such a heritage of unreliable behavior and still doesn’t give you actual performance benefits. If you need a document store use Couchbase, CouchDB 2.0 or Postgres blobs. If you need a cache use memcache. Why Mongo, especially after the latest licensing headache?