There is one thing I don't understand about your argument, Microsoft did not open source their entire stack, but what you're asking of Wolfram would be akin to

There is one thing I don't understand about your argument, Microsoft did not open source their entire stack, but what you're asking of Wolfram would be akin to releasing the whole Windows source code into the wild. Sure Wolfram would still exist in some sense, maybe as a consulting company, maybe just selling support, but it would become a fraction of its current (not huge anyway) size.