Bear in mind that the testers can't say anything, whether it be praising or complaining.
Which makes it one of the strangest closed betas in recent memory.
Ugh, to the public, not to the developers. Although I also can't say how talkative we've been to them either.
When Hearthstone was in closed beta, people were live-streaming it. NDAs are so far from the new normal as to be suspicious, except in cases where IP is involved, and all of the IP of Dominion is already out there. If it's not good enough to let us hear about it, it's better to not announce the existence of a beta test.
Really? Blizzard is the yard-stick?
Man, I got an invitation to Blizzard's most recent closed beta on the basis of my Hearthstone account, which has only a few hours total playing time.
And I got beta keys to give to four friends.
Which is to say that a Blizzard closed beta is about as close to a public beta as you can get.
There are all sorts of reasons for an NDA, beyond protecting IP.
The main one I can think of is that you don't want beta testers complaining about issues with the game that won't make it into the final version, giving potential customers the wrong impression.
Like if they start saying "they've still got the stupid lobby system" we might start to think that MF haven't listened to our feedback on that issue, when in fact a replacement matchmaking system is due to be rolled out tomorrow.
We're all keen to hear how awesome the new version is, which is precisely why the beta testers shouldn't be talking about it until it actually is sufficiently awesome.