If it wasn't for MFC, C++ (which was released in 1983) might not have reached the widespread adoption it did in the 90's.
Yet, I would wager most people wouldn't argue that Microsoft should be mentioned along with Bjarne Stroustrup when talking about the creators behind C++.
I always smile at that urban legend. It belongs to the same place as game consoles use OpenGL for their APIs.
1 - Microsoft was the last C compiler vendor to add C++ to their toolchain in MS-DOS with the 7.0 version of their compiler. Everyone else already had C++ support.
2 - The first generations of C++ developers targeting Windows were using Borland C++ with OWL, followed by C++ Builder. This started to change after Borland's management went crazy.
3 - Before JEE, enterprise distributed computing was done on UNIX systems with C++ and CORBA.
4 - OS/2 had a C++ framework similar ot COM, but more powerful with support for metaclasses and other Smalltalk ideas
5 - The Taligent project being developed by IBM and Apple were based on C++
6 - Apple replaced their Object Pascal code with C for the lowlevel APIs and the C++ framework PowerPlant
7 - The Lisp Machines vendor, Lucid tried to sell a C++ IDE with Lisp like features still not available in modern C++ IDE's
8 - IBM started to move OS/400 code from the PL/I dialect into C++
9 - Many C++ MS-DOS developers were already enjoying C++ frameworks via Turbo Vision
I could provide lots of more examples.
MFC only became usable when Visual Studio moved into 32bits world. And even then, the mismanagement from Symantec, Borland, Watcom and Metrowerks were a bigger reason for developers to move to Visual Studio than anything else.
If developers now complain about the slowness of the modern Microsoft to adopt the C++ standard, back then it was even worse.
Visual Studio was the IE 6 of C++ compilers, with language features for COM and ATL taking priority over ANSI C++ compliance.
As former C++ dev I appreciate all the support the modern Microsoft gives to the community, but having MFC responsible for C++'s adoption in the industry, really?!?
Also AFAIK many of the Rails use cases drive Ruby's design.
So in a way, DHH was influential to get Ruby adopted.