Rarely, systems can be initiated by individuals, but the vast, vast majority are built and maintained by teams.
Those teams get smaller with LLMs, and it might even lead to a kind of stasis, where there are no new leads with deep experience, so we maintain the old systems.
That's actually fine by big iron, selling data, compute, resilience, and now intelligence. It's a way to avoid new entrants with cheaper programming models (cough J2EE).
So, if you're really serious about dragging in "commercial-grade", it's only fair to incorporate the development and business context.
Obviously anecdata, sure, it's just that LLMs for now seem mostly suited for throwaway code / one-off projects. If there's systemic proof for the contrary I'd be happy to check it out.