Many times comments piqued my interest o. What otherwise would look like q boring post
Think of it, if you want, as a random sample of what's going on, like when you do inferential statistics to know something about a too large population
And like other people here said, I found many interesting comments, links and users through this instead of by going through the front page.
I agree that as a method to follow discussions it's not useful due to the large volume of comments posted, and I don't know if it was intended to be used that way back in the day, but it still has its place, at least for me.