In big companies, the why is 80% of the work. I could swear actual dev work is less than 20% of a “developer’s” job at a standard large (non-SV/FAANG/tech-first) company. The rest is holding a lot of really weird organization-specific context in your head to make the right decision.
With my own tiny company, I used to answer questions about my code to support. Supporting the support. I remember doing that when working at big companies too.
Now, my support asks claude about the codebase to answer those sorts of questions. He's better than my memory.
But it answers the what, how, and allows one-off features.
So the guy that wrote might (or might not) still have the edge with the why. But that's not the moat it used to be.