At the bottom of each of these arguments is a "who is accountable" question. You can tell an LLM "hey, use Lean to verify this" or "hey, do a code review" or "hey, write some tests and run them". It might do these things, it might not. You can then tell another LLM "hey, check that LLM A did these things". It might do these things, it might not. Repeat.

You can tell a human (an IC) the same things. You can then tell another human (a manager) "hey, check that IC A did these things". So far, these are the same. But there's now a critical difference: you can then hold those people accountable if they don't. They can be in the critical path. LLMs can't. People can improve. LLMs can't. People can work together. LLMs can't.

This doesn't always matter. You don't need things like accountability or improvement or teamwork all the time. But you do in reliable software.