> Link shorteners appeared as a consequence of the rise of Twitter. With a 140 characters limitation, sending full links over the micro blogging network was almost impossible.
No. The first extremely popular link shortener was TinyURL, and it launched in 2002, years before Twitter existed. Link shorteners became popular because URLs for some websites are extremely long and unweildy, and are thereby difficult to type; they also have tons of puncutation, and are at danger of being mangled by various transports due to line wrapping, escaping, and character mapping.