I seriously doubt that each company that wanted to train an AI on Reddit's data went and downloaded a fresh copy of the data from Reddit anyway. There were already pre-packaged dumps of Reddit's data floating around on archive sites. Still are, so making Reddit's API harder to use doesn't really change anything going forward either. It may make those archives slowly get more out of date, but there are better ways to make an AI knowledgeable about current events anyway. We've learned a lot about AI training in the past year and I think the value that was imagined around data sources like Reddit may have actually just been a brief blip.