I don't think 1.x was trained on porn either?

I seem to remember the issue with 2.x is that they removed all the commercial art from top-notch illustrators from the training data due to the backlash, so it was just way worse at generating great-looking things, which is all the user cares about. So the community stayed on their custom-trained models derived from SD 1.5 (which, yes, often included porn).