Technically yes, but you can use elasticsearch as a distributed key-value store. I use it in production and it works amazingly well for me. Yes, searches may return stale data (one second old by default) but that is not much of a problem in my app.
That sounds both interesting and non-intuitive. Can you go into more detail about how you have been using ElasticSearch as a k/v store?
EDIT: Color me surprised. I didn't see it mentioned at all in the ElasticSearch docs or in their Github repo, but apparently this is a fairly popular thing to do.