The problem is the stealing of labor. Not by you, mind, but by the people who put together these AI codebases. Artists did not put up images expecting them to be able to automatically used to obsolete their job, they expected people to directly copy or save them, which would maintain their IE signatures and stuff. This is why artists really dislike tracing, because taking someone else's creative expression and passing it off as your own is a (subjectively) kind of scummy thing to do that's much worse than piracy or IP theft (not because it's particularly bad, but because those things are like literally not bad at all).

The issue is fundamentally that AI models are exploiting someone's labor to be created. It's just the same kind of labor exploitation we always do but scaled up a bit.