Long time ago there were very few popular databases. Because starting a DBMS was not easy with relational database model. But now with NoSQL database management systems are getting cloned. Numbers of database management systems are growing exponentially.
Now the fashion is, if you are fed up with DBMS which is existing you can write a new one and be a master of it. No matter what ever it is. It may be just a API to reading from or writing to text file. But to be frank there are few good NoSQL databases. But most of them are clones. Clones give nothing to the industry, nothing to the growth of data science.
Data is something valuable to everyone. All of our IT professionals depend on Data. So it is not a joke to play with those useless NoSQL databases. :)