I think the more people that play it the better because me personally I want to experience the game first hand instead of getting my information/opinions based on a stream. Correct me if I'm wrong but aren't the TFP picking a streamer, if so then what if someone doesn't like watching anything from that streamer (so they would just wait until they get their hands on the A21 update rather than watching that stream).
Also, the more people that play the Alpha 21 release right away instead of just a streamer playing it will mean more opinions (likes and dislikes) so this will let the TFP know what everyone loves or hates about the update.