For me, at least.
I joined Twitter a couple of years ago. Primarily I thought it would be a good way to share my blog posts, but I have also been able to converse with some great, like-minded people. However, it is very apparent that few (if any) of my Twitter followers actually click the links to my blog posts (unless I tweet directly to them).
Although I do find Twitter extremely useful for getting news updates from various sources, my main reason for joining has not had the desired result, which begs the question: what's the point?