The majority of business information systems use RDBMS for structured data but that has no link to Big Data.
The sheer volumes of unstructured data make it impossible for RDBMS systems to cope as they were not designed for it. Other architectures are more suited for this like Hadoop.
But beyond the traditional RDBMS vs Hadoop debate, both are not ready to market without lengthy developments & incurred costs. What customer will wait & pay for that even before he's processed 1 byte of data. However there are commercial flat file based tools available like Secnology. Then don't think "magic software" will do the analytics, so use a Data Expert.