What is DOCX?
What Word has saved since 2007: a zip of XML parts, replacing the binary .doc that came before it. It is a page format through and through - paragraphs, styles, revision marks - with no notion of a typed value anywhere in it, so a table in a Word file is text arranged in a grid rather than data.
What is JSON?
The format the web runs on. Nested objects and arrays, real types, and a syntax small enough to fit on a postcard. It maps badly onto a grid, which is why converting deeply nested JSON to a spreadsheet always involves losing something.