Writing has always been mediated, mostly physically. There are things that can and cannot be done in a cuneiform tablet that differ from that for a scroll, and that for a codex, and that for runes on bark, and that for a printed book, and that for a web page.
When we get to the web page, we move from physical mediation — forms or practices or means of production based on the physical properties — to forms or practices or means of production based on the code (another “text”!) that makes that mode of textuality possible.
Let’s talk about how expression of ideas is mediated by the code, analogous to how expression of ideas has been mediated by earlier means of production.