Begin with the job
AI is valuable when a task involves language, perception, variation, or judgment that deterministic rules cannot handle cleanly. It adds little when the job is already well-defined and exact.
A product team should be able to explain why AI improves the outcome. If the answer is only that it makes the product sound modern, conventional software is probably the stronger choice.
Predictability is a feature
Billing calculations, permissions, inventory updates, and compliance gates usually benefit from explicit rules. Deterministic systems are easier to test, explain, and operate. They also provide the dependable foundation around which carefully bounded AI can work.
Build the smallest sufficient system
The best architecture may combine both approaches: deterministic workflows for state and policy, with AI for narrow tasks such as extraction, summarization, or drafting. Technology should serve the product promise, not become the promise itself.