Only so far as you trust your crowd. It only takes one bad actor to poison an entire data set with a few pieces of copyrighted samples, and now the entire model is subject to potential future litigation.

Wikipedia somehow handles this okay. But yes, there will be work to do to address the issue.

How is it different from stock images? People could sell not their work on the stock sites, and it is pretty hard to detect. Or impossible to detect, if you ask some AI model to repaint the image first, before putting it into the stock.

I feel like the amount of training data needed to compete with commercial models would require a large amount of automation to collect, and it's that same automated collection that platforms recently decided to gatekeep against.