I am new to GIS and just want to understand this concept.
Read the document here http://pro.arcgis.com/en/pro-app/tool-reference/appendices/geoprocessing-considerations-for-shapefile-output.htm
The only advantage presently is that it is in widespread use and compatible with the needs of other gis and non-gis software packages
A few other helpful resources
What is the difference between Coverage, Shapefiles and Geodatabases in ArcGIS? - Geographic Information Systems Stack E…
The Top Nine Reasons to use a File Geodatabase
Retrieving data ...