[CHY872]

Because it's a semantic thing. If I tell Twitter that I want to link to a web page, they damn well better link me to that web page, and not what it redirects to, because I've asked them to link me to that web page. I could be using the link shorteners for analytics, all sorts. Maybe I'm targeting different URLs to different users. Yes, for almost all users removing the shorteners is preferable, but the SEO people would be up in arms. The real thing here is that modern browsers don't have problems with links - they don't need link shorteners. Twitter adding t.co to every link is unnecessary - they could just have a hyperlink etc.