I and many others would not have seen her response.  So, why would any of us ever use the comment feature?

I've used it well over 300 times, already.  When I see a post of interest, I also note the comments to see if there are any.  Then, if for nothing else other than curiosity, I click the comments.

As I said before, comments allow a better focus concerning a post without interfering with a total thread.  For example, a conversation might be taking place between two or more at a certain spot in the thread.  One or more of those people may then not post for a month.  Coming back after a month, they might pick up the conversation again, but when they do, it's now to take place amid all of the new and newer posts and ideas, when if the comments were used, the conversation could continue in the context it was originally begun.  It saves a lot of clutter.

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I still don't know how to get to a last post on a thread, though, which is really frustrating....

Since I wrote this answer, I have changed my mind and enjoy using the comment section.  Because of advice from fellow yedda friends such as DYK and WWWW I have to say, I can see its value.