Earlier quoted context omitted.
No. From what I’ve gathered was trained on human anatomy, but not straight up porn. What they tried for 2.0/2.1 was way too overdone, to the point where if I prompted “princess Zelda,” the generation would only look mildly like her. Presumably they just didn’t have many images of people in the training. 1.5 and SDXL both work fine of that front. Fine tuners will quickly take it further, if that’s what you’re after.
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).
What you said also happened, but the main thing was the base model didn't have a great concept of human anatomy. Apparently it was really hard to train for anything else as well.