Is web annotation useful?

Hi guys! We recently created Spade, a chrome extension for web annotation, and released it on product hunt today. Do you all think web annotation is useful? One of our main features is sharing your annotations so people in your team can see your thoughts on articles. In what kind of situations would you all use this feature? What do you all think Spade could be used for? Do you think a web annotation tool like ours should have research capabilities like the features that we have made? Let us know below. Thanks a lot!!