I wouldn't necessarily elevate an expectation of visual and behaviorial consistency to "theory". I have learned that a chair can hold my body weight. When I rest my body on an object that resembles a chair and that I've never encountered, I expect to be able to rest my body on it. This is the foundation of design, industrial or interactive.

We're not debating the outer contours and nuances of this idea. The article presents a cut-and-dry analysis of basic application of it.

You put far too much stock in your own experience and comfort exploring a tablet UI, and yet you seem to hold yourself as more representative as a "real user" than the author. I disagree. I've witnessed people in my personal and professional life get basic things wrong. What you perceive as a button, a data grid, a message window, they often perceive as an indiscriminate arrangement of text, lines, and color. Which is why I think the author's analysis, in those terms, is worthwhile.