True, but in this context, they had a relational database, and the relational database is still there, and isn't going anywhere, so not a big win there. Plus,

True, but in this context, they had a relational database, and the relational database is still there, and isn't going anywhere, so not a big win there. Plus, the real problem is that the correct solution was something that was already boring at the time, memcached. If all you literally are using a "NoSQL" database like MongoDB for is a key-value store and literally nothing else, you don't need NoSQL, you just need a boring key-value store.