Interestingly there was a Ask HN about Amazon using HN for advertising its product recently as well: https://news.ycombinator.com/item?id=18553815. It was around the time of reinvent, which makes sense, but it also made some people suspicious.
Disclaimer: I work at Google but do not post on behalf of my company.
Edit: Removed facetious comment about potentially enjoying being on HN as part of my job.