And just because you've got a clever saying doesn't mean we aren't just dealing the two different kinds of screw drivers. That's the whole point here.
I can store JSON in a MySQL column and you'd say I'm using the wrong tool. But I decided to define a schema instead, then I'm using the right tool? It's pretty arbitrary. Some requirements do lean one way or the other but most of the time there's not much of a difference.
The areas where clearly an RDBMS is the correct solution or where NoSQL is clearly the correct solution aren't an issue. I think there are huge areas that do overlap. NoSQL is being advocated in far more situations than just where it's clearly the correct solution.
Yes they both store "data", but there are types of data that one is well suited to deal with, and alternative types of data that the other one is better for. On my team we've already split out data into two sets, one that lives in ACID RDBMS and one that lives in NoSQL.
If you are dead set in using one solution for everything, my pity for you.