Since when does every use of a database involve handling datasets in a way that needs experience and "algorithms". A key value store can be used as... a key value store if need be. It doesn't need to be crazy science.

Once you start scripting your K/V store, its not a simple K/V store anymore.

I am not against databases with scripting capabilities and I do not think javascript/front end developers are per se naive, but I've far to often seen the naive assumption that just because its javascript, everyone can handle it.

This isn't true. Once you have tens of thousands of records, a poorly written algorithm or data structure is going to lead to O(n^2) behavior. That hurts. Even small sites can hit this amount of database records with ease.