AI-generated code still requires software engineers to build, test, debug, deploy, secure, monitor, be on-call, support, handle incidents, and so on. That's very expensive. It is much cheaper to pay a small monthly fee to a SaaS company.
How often do software projects underestimate their cost and timeframe?
The LLM-written replacement may prove to be more expensive, but may appear to be cheaper initially when all of the costs and budgets are hidden in the “fog of war”.
How effective will vendor messaging warning clients away from writing their own vendor replacements be? Of course a vendor will play up their strengths and will try to play up the clients’ weaknesses. It’s like asking a used car salesman to give you their opinion of a car on their lot — they aren’t seen as neutral observer.