It may be forbidden or unappealing to venture capitalists, or exclude you from important avenues. Adobe for example explicitly forbids open source from touching the Photoshop SDK, for example. I believe Propellerhead is also anti open source as I recall.
Most people go for the VC money. We are the crazy ones 
i know, tho i would say it isn’t crazy, seeing the success of open source projects in many fields. the internet wouldn’t be what it is without open source software and open protocols. server-side it runs largely on linux, while client-side android is one of the most successful platforms. firefox is open source, and most of chrome is. vlc is open source, and many other multimedia projects use ffmpeg libraries. in music, vst is an open source technology, as is the flac format. the list goes on.
i think it is fair to say that vcv rack is one more instance of open source enabling rapid growth of a community and an ecosystem of third-party contributions (plugins in our case).