Yes, for development we don't need LLM factories. At a code level there is always need for design-pattern factories, but that's different IMO. What people mean by factories is custom agentic harnesses.

Now, one space for custom agentic harnesses is anything customer facing: There is a communication flow, standard operating procedures, etc. You make the harness once, and can use it to "produce" the same product/service experience for many customers. But I'd not call that a factory.