Is this entirely true? Clearly cleanup of event names like "loadedmetadata" is related to the audio element but '_bubbleProfilingEvent', '_logEvent', and general .unbind calls are on backbone-related objects, yeah?
One area where backbone is lacking is lifecycle management. You do sometimes have to unbind things in order to prevent leaks. Backbone is very minimal in this regard. At Rdio, we've built our own tools on top of Backbone to abstract lifecycle away from the developer as much as possible. That being said, that weakness isn't illustrated in the code example picked by the blog post.