The different Cloud Vendors had been offering Big Data as a service for quite some time. Athena, EMR, RedShift, Kinesis are a few of the services from AWS. There are similar offerings from Google Cloud, Microsoft Azure and other Cloud vendors also. All these services are native to the Cloud (built for the Cloud) and provide tight integration with the other services from the Cloud vendor.
In the case of Cloudera, MapR and HortonWorks the Big Data platforms were not designed with the Cloud into considerations from the beginning and later the platforms were plugged or force fitted into the Cloud. The Open Hybrid Architecture Initiative is an initiative by HortonWorks to make their Big Data platform more and more Cloud native.
It’ll be interesting to see where this goes.