I can't read Hebrew either! But the way these books were typeset was to balance commentary with the text. For instance, you can see that the right page has a pretty substantial chunk of scripture in the middle (the central columns are scripture) and the left-handed one has only a couple of lines. This style doesn't have the central text with commentary as an optional note, it's a blending of text and commentary. So one "page" of text might be 100% Tanakh and the next might be 10% Tanakh and 90% commentary. Rendering either one of them as a contentious text stream (or even interwoven paragraphs) loses some of the authorial intent.
Obviously this is a pretty specific literary tradition and most marginalia works exactly like you describe, but I think it's worth remembering that our experience of text being one way is often more about the texts we've happened to encounter than any limits to the diversity of how humans have written.
The Chinese religious text looks basically the same as the right-hand page. It's surrounded by commentary on three sides instead of four sides, but that is a minor difference.
The left-hand page is obviously different, but it's not clear to me how much I should think of it as text and how much I should think of it as artwork / talismans.
Anyway, I agree that the commentary is presented as being at least as important as the text, but I don't see that as contradicting what I was describing above.
> So one "page" of text might be 100% Tanakh and the next might be 10% Tanakh and 90% commentary.
This style is also common in contemporary legal documents. (I searched briefly earlier for a good example and didn't find one.) A page will usually not be 90% footnotes, but it's not so rare for a page to be more than 50% footnotes. I think this is a pretty natural outcome of the fact that some parts of any text attract much more commentary than other parts. Despite the very high volume of footnote material in these documents, though, they are always presented in a manner that suggests the text comes first and the footnotes come second in importance. For example, the footnote to a particular bit of text may not all occur on the same page as the text it footnotes.
I would argue that the difference between the religious texts and contemporary legal briefs is that the commentary really is more important than the text in the first case, and really isn't in the second case. The religious texts have been preserved for so long that they don't have much meaning left independent of the interpretive tradition that the commentary provides.
But your own personal notes on something you've read are unlikely to be as centrally important as the accumulated interpretive tradition associated with a multi-thousand-year-old text. If you wrote it in the margin initially, keeping it in the margin seems fairly safe. That commentary you see printed around the scripture on the right-hand page didn't come from the book owner.
