Some people choose nosql alternatives because they've spent time analyzing the performance of a proper relational model and have determined that an RDBMS will generate too much overhead for their data load and consciously accept the tradeoffs involved in giving up automated referential integrity.
Most people, though, choose nosql alternatives because they're too lazy to learn how to model data.
Most people, though, choose nosql alternatives because they're too lazy to learn how to model data.