Comment by shevy-java

Text and text files are simple. I think this is their number #1 advantage.

There are limitations though. Compare a database of .yml files to a database in a DBMS. I wrote a custom forum via ruby + yaml files. It also works. It also can not compete anywhere with e. g. rails/activerecord and so forth. Its sole advantage is simplicity. Everywhere else it loses without even a fight.