Large group rides are overrated, but I definently enjoy rolling with the usual suspects that I know and trust. Crashing is never off the table, but it can be mitigated with competent riders.
A failure I see more than anything is a lack of understanding between new riders and veteran riders on what constitutes a ride. While I firmly stake my flag in the soil of "personal accountability", some folks get in over their heads. The difference between riding a bike to work every day and riding a bike in the twisties is massive. It is not the same thing in the slightest to the average rider.
I have a friend that has been riding for decades, but he commutes. When we hit the mountains he can't begin to stay on pace with the rest of us. He just doesn't have that skillset because it isn't how he rides. He can pilot a bike, but he has to do it at his own pace. Luckily, he's mature enough to recognize this and doesn't try to keep up. That plays a major role.. personal accountability and leaving ego at the house.