some people can't put in the time to gather competent party members and don't have ingame friends to fill in. Some people don't have time to run things over and over to get it right. Some people just want to watch the story unfold or get the gear and be done with it. Some people just want it checked off and don't care how that gets done.

People have all kinds of reasons and considering this affects everyone else very near to nothing, i don't see a problem with it. People like that don't dutyfinder often and will quit early if the run doesn't go well, so they aren't a huge factor.