This was just speculation on my part.
Harris recently announced the removal of session streaks from the app. The feature is prominent on many popular meditation apps and Harris removed it when they recognized that it was the cause of suffering when app updates reset the streak.
This suffering is a byproduct of the attention market. Twitter and Facebook exploit this suffering in many ways to keep you engaged with their platform. Attention seeking is considered an anti-pattern when abused.
Whether or not group meditations are the result of similar attention seeking is the speculation on my part.
Signal and Tusky are examples of non-profit social media apps that try to remove anti-pattern features from their products.
As a result they are not as widely adopted by their corporate counterparts, WhatsApp and Twitter.