They've implied that they're not going to sell the Steam Machine at a low margin because they're worried about people buying the Steam Machine for general purpose computer use without buying games. I'm not sure that's a rational fear. If you subtract the GPU, you can get an comparable Beelink for ~$350. ~$500 would be the zero-margin price for a Steam Machine. It seems to me that the only people willing to pay an extra $150 for a mid-range GPU that's not good for AI would be gamers.
Not to mention that the Beelink comes with a Windows license, and the Steam Machine doesn't.