In this article (bit.ly/2zLX8MZ) about bike fit, the author supports that
When you fit a bike perfectly there is
no need for headset spacers.
What is your opinion?
In all seriousness, just to say "a well-fitting bike doesn't have any headset spacers" is
ridiculous because you can achieve the exact same fit with a horizontal stem and spacers, or with an up-angled stem and no spacers. If their contention is that the right frame size would lead to a correct fit with a more-or-less horizontal stem and no spacers, well maybe but you're still at the mercy of what the frame makers are putting out.