It probably ignored hundreds of thousands of "by using this site you consent to our Terms and Conditions" notices, many of which probably would be read as prohibiting training. But that's also a great example of why these implicit contracts don't really work as contracts.
OpenAI scrapped my blog so aggressively that I had to ban their IPs. They ignored the robots.txt (which is kind of ToS) by 2 orders of magnitude, they ignored the explicit ToS that I copypasted blindly from somewhere but turns out it forbids what they did (something like you can't make money with the content). Not that I'm going to enforce it, but they should at least shut up.
