Just saving it from LinkedIn:
The real difference between SQL-based (and other relational databases) and NoSQL glorified KV stores is the presence of algebraic structure (i.e. Codd algebra). Algebra is basically all about transformations between equivalent expressions to arrive to a desireable form (i.e. simplified, or factorized, or whatever the goal is). These transformations have another name: optimizations.
Basically, when you have a real SQL database, you have ability to optimize execution plans. Which could easily yield orders of magnitude of improvement in performance.
(And, yes, modern relational databases (i.e. Snowflake) do internally convert semi-structured data into tabular form so that the optimizations are applicable to these as well).
If I had something to say about this, it would be something about stable, dependable performance having a value of its own. That is why TokyoCabinet was such a revelation and prompted the NoSQL revolution, which later ended with Mongo and reaction, like any revolution. But this is not my field, so let's just save it for future reference.