What is the point of making hardware synths on a Pi when you could just make a VST?
Do you think that making a VST is a realistic alternative to the linked instruments in the submission article? I'm guessing they're building hardware because they want something physical, it's pretty self-evident isn't it?
The precise and exact sound is less interesting, how you're able to conjure it at just the right moment and with precise controls tend to be more interesting for me personally.
So if you already have a VST, but you also have customers asking for actual hardware, why not slap your existing VST onto a Pi, and ship your "hardware" synth with this Pi inside? You end up supporting one software product across both lines.
(Only a very tiny minority of people want to record music. Music is mostly a realtime experience.)