It introduces a dependency on the shortening service, if the service vanishes the link breaks.
It allows the shortening service to track clicks on the link.
It obfuscates the target of the link.
It allows the shortening service to track clicks on the link.
It obfuscates the target of the link.
The second a popular link shortening service goes belly up I'm sure someone somewhere will buy the domain and setup a program to redirect all the shortened links to an ad-ridden search page.