Although throwaways are generally considered acceptable, especially on Reddit. Without some means to enforce single account registration or a real name policy, the same problem exists.
Persistent usernames on Reddit create a culture of identity on the site. Throwaways with no user history that post inflammatory comments frequently tend to get called out and downvoted. That's a very different setting from something like YikYak.
It's worth noting that Reddit exists to discuss topics, hobbies etc. Yik Yak doesn't have a defined purpose to the same extent Reddit does.
This lack of definition combined with the geographically-centered design (you know your audience) makes Yik Yak far more dangerous than Reddit IMO.
There are a lot of good use cases for throwaways (suppose a former cult member wanted to share their experiences, for example). And the fact that an account is brand new is also a data point. You'll notice that Reddit/HN have produced a lot of insightful/informative comments from throwaways.
"people whose opinions the majority of voting members disagree with"
Still true, but I think it is probably easier to allow controversial or less popular opinions in a ranked system than it is to deal with harassment in an unranked system, given the propensity of the voters towards "good." The harassment seen on reddit is very different from the harassment on Yik Yak, Juicy Campus, etc. That guy they thought was responsible for the Boston Marathon bombings, for example.
Of course, Yik Yak and Juicy Campus were designed for this LCD speech.
