My best guess is that it flew under the radar. The Kaggle dataset has 'only' 10,000 downloads, and the article itself probably doesn't have that many views. Still, this seems pretty far beyond the pale. Given the other case of AI-related plagiarism by Microsoft that was on the front page[1], it seems whatever review process they have for content that is published by their employees, if there is any review process at all, is deeply flawed.

[1] https://news.ycombinator.com/item?id=47057829, "Microsoft morged my diagram". It was in a discussion there that someone pointed out this article linking to full downloads of the Harry Potter novels, which I thought deserved more visibility.