4chan's failure to me has little to do with perceived anonymity, and a lot more to do with the culture of an online community, what is tolerated within that community, where the red lines are, and how this is enforced. And "gamification" plays a role, i.e. virtual online points of some sort, be it "likes", be it "karma", be it "upvotes".
Compare 4chan to HN, which is also open to anybody like 4chan, allows anonymous (or rather pseudonymous) posting, and has a somewhat sizeable community of people posting and many more "lurkers" just reading.
Unlike 4chan however, HN does a reasonable job - in my opinion - of being clear what is allowed and what is not, enforces these community standards quite vigorously most of the time, through moderation not just by moderators but the community (flagging), and generally stops outright abuse and harassment, and more often than not stops trolls and people accidentally starting flame wars. That has to be balanced against not over-banning/over-flagging content, which happens, too. Not everything is perfect in the niche that is HN - nothing ever is - but the contrast to 4chan is quite stark, even to the supposedly more moderate and "sfw" 4chan boards like /g/ (technology).
Gamification is a double edged sword. On one hand, it may encourage people to instead of their actual views post quick quips or hide their true opinions and opt instead to just say what they believe the community wants to hear. On the other hand, in places like 4chan which lack such gamification, you don't have to fear burning your reputation as nobody has a visible reputation, which may encourage people to cross lines as there is no way for the community to sanction such behavior.