I can think of only one advantage i.e. it can run on a server without any back end database support. Many free hosts does'nt offer database(like mysql) support, and this script may be useful in those situations.
its not a bad idea to store the information in text files with php, but it can get messy and slow loading if you dont organize/sort them the best way. I would go for MySql but i would try it if i really would like one without mySql.