I'm only discovering Literate Programming today, but you seem very familiar so I might as well ask: what is the fundamental difference with abundant comments? Is it the linearity of it? I mean documentation type comments at the top of routines or at "checkpoints".
I'm particularly intrigued by your mention of keeping old code around. This is something I haven't found a solution for using git yet; I don't want to pollute the monorepo with "routine_old()"s but, at the same time, I'd like to keep track of why things changed (could be a benchmark).
A good way to think about it is {Program} = {set of functional graphs} X {set of dataflow pipelines}. Think cartesian product of DAG/Fan-In/Fan-Out/DFDs/etc. Usually we write the code and explain the local pieces using comments. The intention in the system-as-a-whole is lost. LP reverses that by saying don't think code; think essay explaining all the interactions in the system-as-a-whole with code embedded in as necessary to implement the intention. That is why it uses terms like "tangle", "weave" etc. to drive home the point that the program is a "meshed network".
To study actual examples of LP see the book C Interfaces and Implementations: Techniques for Creating Reusable Software by David Hanson - https://drh.github.io/cii/
I'm particularly intrigued by your mention of keeping old code around. This is something I haven't found a solution for using git yet; I don't want to pollute the monorepo with "routine_old()"s but, at the same time, I'd like to keep track of why things changed (could be a benchmark).