DefinedCrowd is pretty successful actually, just so you know this isn't sour grapes. And it isn't about a meeting 4 years ago, the very first line of the article says that Amazon was an investor (at seed stage, probably a few hundred K).

So the problem isn't that someone heard about DefinedCrowd and decided years later to make something like it. Amazon made a significant investment in an early player in this space, and then started building a direct competitor while still presumably having both access and influence over that company. Doesn't seem responsible or ethical to me.