Because each comment that a person posts on Cake is its own separate post, there is a major noise to signal ratio issue when trying to back track through someone's older posts on their profile page. I don't know a solution but one idea (that may not be feasible) is a second profile page that collapses the previous conversations in which a user participated.
The current status is that the first post one comes to in a given conversation is the last post made by the user in that conversation. If that user has posted twenty comments on that topic, one has to scroll past that conversation twenty times. Chris MacAskil, as one example, often posts a large number of posts in a conversation that really interests him. Try scrolling back through @Chris's profile page and you will quickly see what I am referencing.
I'm not sure if there is a way to make this more user friendly but thought that I would mention it for your consideration.