> it's harder and harder to spot, especially when the use is "thoughtful".

It's not, only suckers think otherwise. The more you consume, the easier it gets to spot them, and also you get bored of it quicker. Which is fine for an actual tool.

IMO: if you think it's problematic if people could spot AI tool marks, you're not actually viewing or using AI as a tool. Rocket scientists aren't ashamed of using high end 5-axis CNC or SLS laser metal 3D printers to make rocket engines. Good machinists can tell how they were made, and that should mostly inspire confidence. If someone thinks the tool marks for a specific type of a tool needs to be hidden for the artifacts to be trusted, there has to be something wrong somewhere with the tool or how it's used, or both. Likely both.

Anyone looking at a Boeing 787 can tell that it flies on a pair of turbofan engines, and it's cool. Most people looking at AI images can tell it's generated using AI, and some can even identify models used, and that is NOT cool. That should be a strong enough sign that something is wrong with AI.