The first part of your post made sense until you said "The right way to look at it, imo, is to see RDBMS as specialized systems". RDBMS have a lot more feature

The first part of your post made sense until you said "The right way to look at it, imo, is to see RDBMS as specialized systems". RDBMS have a lot more features and support many more usage scenarios out of the box than any NoSQL systems and SQL offers more features as a query language than any other NoSQL query languages. Of course, NoSQL query languages are simpler than SQL by design because the programmer is expected to write a program or a script for complex queries instead of using the query language. But then, you have to write your own execution plan, and think about atomicity and consistency, etc. NoSQL are clearly the specialized systems, not the general ones.