This mirrors my experience. Vibe-coding one-off, low-risk apps, it's been fantastic. Trying to take the same approach when implementing features in massive legacy codebases has been an utter nightmare.

Exactly, and in most companies engineers have to implement feature in an existing codebase and hardly get to work on a completely greenfield projects. In my experience most of the time LLM take a quick dirty shortcuts to implement thing in a legacy codebase. It work, but not efficient and would collapse under heavy load, especially DB query implementations