[HodGreeley]

NoSQL databases arose in response to the growth and change in data use, driven largely by the web. Typical needs cited include scalability, availability, performance, and flexibility. Development has been going on for a long time.

I think most would agree there is no longer a one size fits all (or even most).

Realm (and I know someone will correct me if I'm wrong) started out as an on-device only replacement for relational-style dbs focused on ease-of-use and performance.

It's not the only one. Couchbase Mobile is a NoSQL stack that has an on-device db that's also easier to use, and has focused for many years on getting sync right (which is a hard problem).