Why not building on top of existing full text index/search engines? Why would I choose this over something like Kibana (http://rashidkpc.github.io/Kibana/ http:

Why not building on top of existing full text index/search engines? Why would I choose this over something like Kibana (http://rashidkpc.github.io/Kibana/ http://rashidkpc.github.io/Kibana/) that provides me with all this and more, is built on top of existing capable, scalable open source products, and is itself free and open source?