Because it's a trial. If there is compliance and interest -- we would certainly open that number up at a later date.
Not everyone is gonna be interested in EVERY topic they are invited to and we want to cut down on the alerts that people receive..
Are these threads going to be moderated and if so why?
Because the object is to promote more moderate cooperative discussion. And to allow people to explore serious topics with folks they trust and choose without the ever-present interference of trolls and opposing zealots. If you want private discussions -- you can't beat PMs. If you LIKE the constant warfare, trolling and personal sniping in EVERY other USMB thread -- you probably wouldn't use it.
There's no reason why all these threads need to be echo chambers with like-minded people. Although they can be. One hope is that folks will find trusted members "of the other side" to bring in to balance discussions
My personal opinion is that
these Invite Only would require VERY LITTLE if ANY moderation by USMB staff. Other than intruders who simply don't read OPs or don't know what Forum they are in.