Formerly we entertained a number of participants who seemed angry at everything all the time while now many of them seem absent and I am wondering if that's because of the general drop in activity

Formally (nor formally but qua meaning) this is a weird sentence, Dale. It's more likely the other way around. If (just a supposition) there is a drop in activity, it might be the other way around; because the angry young men have left there might be a drop in activity. ( me no see it )