This is something of a circular argument. Bob doesn't waste energy on on-call duties, so he implements more features, so he's a prolific engineer, so he doesn't have to waste energy on on-call duties.
Yes exactly. I'm not sure whether Bob is a hyper productive engineer, but in any case, Bob is an engineer hyper focused at shipping new stuff out the door quickly. Which is great! We need Bobs. But we also need the company to run and scale, and Bob might not just be the right guy for that.