How is that misleading? Using RDBMS as your primary data store is the decision that people reading this are going to benefit from. When it comes time to cache

How is that misleading? Using RDBMS as your primary data store is the decision that people reading this are going to benefit from. When it comes time to cache and optimize for things like search, that's when you use the additional technologies. It's a huge mistake to think that companies that are using Redis/ElasticSearch/MapReduce are doing so to cover up for the wrong decision they made of going with an RDBMS. The RDBMS is their source of truth, everything else is just an indexing mechanism.