I wanted to wait a while until I shared why I started the Just Three Words thread.
The game has been very useful for me. Like Nick and Bronwyn noted, it is an "easy entry" or rentry point that does not require as much investment as entering into a full discussion thread. So it may pull some folks who were on the periphery closer to the center.
For me the distillation into a few words also helps me see what is really juicy for someone. It asks us to get to something essential. It can be challenging.
I also like to see how people riff or improvise off of each other, giving me a feeling of connection.
It also supports discovery. (See the conversation emerging here)
Finally, it is light. If you skipped the thread, it is not a huge loss. Oline there is so much we CAN read, sometimes it is exhausting. So if I peek into a game and it is not for me, I can rest a little easier when I walk away. That might seem contradictory to what I just wrote before, but that's how I feel. :-)