The ELI5 is that this is more PR astroturfing by the Handshake team, like the four or five other links they have posted to HN over the past two days. After only a few hours the bulk of the comments are by people close to the project telling everyone else how it will solve all problems and provide digital ponies for everyone...
I'm not a member of the Handshake team, and I don't have control over what comments get posted. This is a Show HN - I am sharing something I have helped make, that other people can play with. That was my only intention, and I've atttempted to follow the guidelines here: https://news.ycombinator.com/showhn.html
That said, you are probably right. It doesn't surprise me that there is a lot of Handshake-related activity on HN right now. The project was conceived over two years ago, and today marks its second week of existence and the first day that people can actually try it out. Respectfully, is it possible that most of this is genuine interest/excitement in a new project instead of, as you put it, "PR astroturfing"?