The kinda gross bit is that the hard-boiled eggs end up with a flat end, quite unlike a normal heard boiled egg. As it cooks, the egg fills the plastic container and cooks with a flat top. How do you make a deviled egg when the finished product stands up straight instead of lying on its side? It doesn’t save any time or improve on the product at all. Mother Nature made a nice little package for the egg; why mess with it?
I don’t know. It is just so easy to put some eggs in a pan of cold water, bring it to a boil, take it off the heat and let them sit, untouched, for 20 minutes. Perfect every time. And, easy to peel as well. There is no need for extra plastic do-hickies in my kitchen junk drawers.