[hrkfmud50k]

spark is far more testable and composable than sql! and you even get static typing checking. plus i can read data from anywhere - local fs, s3, rdbms, json, parquet, csv... rdbms could not compete

[adrianN]

Many (most?) DBs have no problem ingesting json, parquet, csv etc from S3. Some can query those formats without first ingesting them.