Everyone KNEW building a heavier-than-air self-powered vehicle was impossible. Then, everyone KNEW you could never fly across the Atlantic non-stop. And it would be impossible to fly around the world non-stop. Ok, sure, those were overcome, but we all know it’s impossible to fly humans to the moon and back. Or how about how we knew it would be impossible for a helicopter to fly faster than 250kts?
Everything is physically impossible until someone proves it’s not. Then it’s obvious it was possible all along.
This is a tech demonstrator doing exactly what tech demonstratora do: prove something is technically possible. They aren’t supposed to be viable commercial products on their own. They spur refinements to the concept until a viable product is possible. It’s a bit of a chicken vs egg: until it’s shown to be technically possible, the technology for a viable product is never developed.