It happens quite often, yes. They are concept artists and designers but they share their own stuff. And just now I opened up Discord and skimmed through some art, pixel art and drawings channels in the many servers I'm in and saw a lot of art that I doubt anyone is trying to sell. People just love to share their creations.
Yes if you are friends with and deeply networked with professional artists and designers, you'll see a lot more hobby art. Most people are not friends with even one (never mind several) professional artists though.
This scenario is irrelevant to my main thesis anyway, which is that people principally do not develop artistry to the levels required for strangers to care about it without doing so as a professional pursuit.
That you get to see the exhaust and byproducts of such a professional pursuit isn't a point against it.
