Unfortunately the world's not made of round holes, round pegs, or square holes and square pegs; sometimes I use a round peg in a hexaganole hole cos they don't have the hexaganol peg in my size and it damn well fits and holds things together just fine thank you.
I do believe this should be interpreted: CRT is classifiable as a framework, even if it is not object oriented - after all it has its interface and its structures to be used in its context.
The same goes, in my opinion, for Windows API, OpenCV, Boost, STL... any coherent set of libraries.
That way I answered I use only one, even if actually it is a set made of Win API, CRT and STL in rare cases (must interface with VB6 AND stick to VC++6, which has an incomplete and bugged implementation of STL).
Yes, I do love to have the best framework or language being used for a purpose, software or application. But, mixing everything up like C++ for performance of services, C# for simplicity with networking, DirectX for graphics and so on and so forth, is never a good choice.
I do use a programming language and intermix a few frameworks or write my own if I think I may be leaving the context. To solve this, I usually select the programming language in the beginning, then I stick to it. Each language has millions of users, take it as C++, C#, Java or whatever new language may be going on (no Python, that I don't have faith in*, so is the case of Swift). The same thing happens, every frameworks or library tool has already been written. Try to Google for a while, you will find one, if not, then read Wikipedia's guide and write your own library, oh yeah, don't forget to write an article on CodeProject about your success.
Newtonsoft.Json is one of those frameworks, when I am writing an application, I only download and deploy this one package, otherwise I try to write my own modules or .NET has it built-in; Oops, I didn't mean .NET-only!
*Swift as far as I have used it, once, executes in the global scope, and well there was no need of main function. What kind of retarded person would believe Swift is programming language? Apple has many cards up their sleeves, I'm telling ya!
The sh*t I complain about
It's like there ain't a cloud in the sky and it's raining out - Eminem
~! Firewall !~
I don't see any difference between the first and the second option (is it possible to work with just a single framework, assuming you want to save time and money?). But nevertheless I chose "we need one framework". We must not spend most of our efficient time working around with a new framework and getting used to it. Rather, I would choose a framework I had worked with before to solve my problem (I am a student; I don't have working experience, but I do have programming experience).
So, I don't go for a new framework unless absolutely necessary.
Of course it is much better when you have single framework (e.g. compare android sdk with web development) which achieves all the tasks in a nice way, instead to have to learn dozens of things like you have to with web development!