Honestly.... I'm a 31 and I don't blame anyone. I think the only exception would be if you had a fully upgraded Ghorn and were only doing Crota CP. The abyss is pretty hard as a 31, I could see the bridge being bad as a 31 and Deathsinger could be hard as a 31 just because of all the mobs. But With Crota CP your only job would be to shoot the Ghorn so that part is understandable. But lvl 33 enemies on lvl 31 guardians is a rekt fest.