I don’t see people driving engines around, since that is impossible. You actually need the rest of the car around the engine to have it function as a drivable vehicle.

It is a pretty practical distinction.

Of course. But most people don't buy an engine, ever. They don't have one laying around. They buy a whole car, every time.

So, since apparently I may need to clarify my actual point: For most people, an LLM-plus-agent-harness is just "LLM" or "AI". If you're trying to build one, you care about the distinction. Ditto if you're a pedant. But most people are not either of those things.