That is for the data store itself, and doesn't mean that the database is NoSQL or not. MemcacheDB for example is a NoSQL database that uses BerkeleyDB as a datastore. No different than you'd use InnoDB or RethinkDB with MySQL.
Awww.. you mad... I'm so sick of hearing about all these "new" technologies that are so revolutionary, but can't hold a candle to postgres and memcache.
Despite what the brochures tell you, a "degree" from DeVry and 3 hours in a Ruby book doesn't make an architect, and this is one of several "revolutionary technologies", like Ruby, that won't scale and will wither and die.
Assuming you have the most efficient code possible, the efficiency and speed of the interpreter can still affect the ability to scale an app.
Another thought is, the interpreter may or may not have scaling / clustering available, be it through a built-in functionality or an external queue or something.
Sometimes we have to code around interpreter/speed issues. I work in the JVM languages sometimes. I have to do things differently directly in Java if a particular JVM language I use isn't cutting it. Same goes for ".NET", which is over 30 some languages.