Because big data doesn't faintly refer to strings of numbers, but also to text, images, video, and so on.

Big data, or giant data, refers to information that is so large in size that it cannot be captured, managed, processed, and organized in a reasonable amount of time by the current mainstream software tools to help businesses make more positive decisions. (In The Age of Big Data by Viktor Mayer Sch?nberg and Kenneth Kukier, Big Data refers to the use of all data without shortcuts such as randomized analysis (sampling).) The 54V characteristics of Big Data: Volume (large volume), Velocity (high speed), Variety (variety), veracity (authenticity). Big Data requires special technologies, including massively parallel processing (MPP) databases, data mining grids, distributed file systems, distributed databases, cloud computing platforms, the Internet, and scalable storage systems.