Until the "Club Ride" feature comes online, and we see all the details as to how those will be set up, we do meetups. Invite people from the club to ride along. Now, some of those people average 20+ MPH on the road, while others average 13 MPH. So, the meetups are configured as "everyone stays together". Fast riders can give themselves a workout at 4 w/kg, while casual riders pedal at 1 - 1.5 w/kg, and everyone stays together within the meetup ride.
The only group rides I'll do on Zwift are the ones with the fence out front. Go too fast in front of the ride leader, and it's bye-bye, so there is no incentive to sandbag your way into a 2.0 w/kg ride, when you intend to ride at 3.0+ w/kg.