a) You'd just write your take next to the link, instead of hiding it behind. Your example is far-fetched.
b) This is obviously meant for ads. (And the examples on their landing page make that perfectly clear.)
Quote: "You can essentially advertise on any website for free!"
B) That's cool that some of the uses are advertising, but I'm not going to. I'm not trying to sell some product.
You don't know what you're talking about. If I follow someone on twitter, I want to know what they are up to. If someone has an event or product, or something else they think is relevant to the article, then I want to know.