They both let you have assets in your game without making them.

Sure they do: stock assets are the most obvious market that AI is taking direct aim at in games development, and the AI tools on the game dev market were largely trained on stock assets. If you need anything from a sound library to a 3D model to an animation to an icon set to background music to network gameplay code… sure you can get it through stock asset marketplaces… but AI tool vendors have ingested many of these stock assets and hope game developers will buy their tools to generate assets rather than buying the stock assets they built their tools with.