But is that point dragging in objects actually nothing? How is that space barrier created? Probably by focusing Chakra into this point, forcing the space to distort at exactly this point. Distortion of space can't happen out of nothing. You need a force to move something from A to B. Even if it's Chakra in this case, which is focused at the point Kakashi aims for, to let the space distort.
We can speculate what Obito exactly did, but in fact, he did cancel Kamui. Analyzing the situation concretely while keeping in mind how Obito's version of Kamui actually works, there is no need to jump at conclusions. We know from Obito's Kamui that it works on self range, absorbing himself and the objects he gets in touch with. Yet, The Kamui aimed at the Mazou's head was canceled. At this point, we didn't even see a reversing progress which let the Mazou's head dragging out of the dimension it was dragged in. The process of Kamui simply stopped, while Obito's physical body was present in their dimension (note, that Obito dodged Naruto's attack physically instead of letting it pass through him in exactly the time he canceled Kamui).
And that example can be projected at the Yata's abilities perfectly. You called Kamui "nothing", a simple distortion of space at a specific spot, moving an object to another location. Yet the effect itself was stopped. And here, the Yata's ability comes into play. It can change every of its properties to alter its attributes in accordance with the attributes of the attack. It adopts the power of the power which affects the shield in some way. If Kamui starts to distort the space at the mirror, the mirror on the other hand could adopt this force and force the space to distort in reverse. I recall what Obito did - exactly the same. He stopped the space from distorting at the point Kakashi was aiming for. That proves, that even this technique is based on a force which forces the space to distort from begin with.
Our beliefs are based on how we both visualize these two powers to work when being confronted. Kamui can drag this shield to the other dimension. Yet, nothing proves my imagination wrong, whether it sounds absurd or not. If Yata was said to be a supernatural item that negates any attack no matter by what it is hit, I would agree that it has no mean to trust mere hype. But in this case, I have my reasons to trust the ability given to the shield, when at the same time, a way to cancel Kamui was indeed given. Its counterpart, the Totsuka blade, also proved the abilities which were displayed in the Databook. And if the Manga didn't show that even an immortal Uzumaki with Rinnegan loses his power immediately and is freed from the complete control of the Edo Tensei's caster the moment this weapon stabs him, starting to dissolve, no one would have believed in such a power, basing their opinions on Orochimaru, who could struggle and put out the Kusanagi blade while being stabbed by the Totsuka blade. I think you get my thoughts.
The case is, that both these weapons were portrayed as supernatural.