The thought process and conversations that produced the code give insight into how to more generally produce code of that kind. Typically code currently in use

The thought process and conversations that produced the code give insight into how to more generally produce code of that kind. Typically code currently in use is in continuity with code that was previously used, either as a system dependency or conceptual dependency. So it's still useful to have history around, like it would be to have comments in current code.