The Magpul sling functions as a single point but has a clip mount that quickly converts the sling to a two point if you need to go hands on and snug the gun up. Magpul and a few others use that design and it works fairly well. Sling systems are trendy like shooting stances. What was cool yesterday is not tacticool today. You gotta stay in fashion if you want to roll with the cool crowd.

Several companies make clamp on rear sling mounts that clamp to the extension tube at the base of the upper receiver. How well they will work with metal against plastic is the question.