I don't know about this. I think it's wholly possible that people derive inspiration and perspective from Dribbble, Behance and similar sites, and use that inspiration to attempt to solve actual business problems in UI/UX, the specifics of which are never posted to Dribbble, either due to NDAs or more likely, because it would be incredibly boring for the average Dribbble user to look at.

I don't believe Dribbble has portrayed itself as a site to showcase business case studies. A lot of the time, it's simply a repository of design samples or off-work personal projects. And I'll admit, after a long day of looking at dull wireframes, it's simply a relief to look at a fun UI mockup animation, even if it might not work in a real-life production app.