Even the most AI-positive teams prefer human discussion when things get that tough. Given enough time, things will "click" for humans. LLMs don't work that way.
Even a team of all-new unfamiliar devs forced to study an old codebase will eventually figure out what it was about and pick up tons of nuance the LLM cannot. This is the nature of writing. It exists in a time and place beyond the pure literal text. Humans live in this context and can get into the headspace of the original dev(s).