What's the benefit of a link shortener, these days? It made sense back before Twitter had one of their own. And I know that some people use it to get link analytics. I've also occasionally seen it used for printed materials, to get pretty URLs that are easy to hand-type. People also use it for malicious purposes, such as hiding malware, or disguising referral links, or otherwise trying to obfuscate where a link is go…
They are useful for links that need to outlive the infrastructure they are hosted on. Think about them as a layer of abstraction. Ie. Links in paper published to a journal like nature. It might be valid for 10 years but the links embedded in it will rot quickly as organisations change cms's, domains names change. Organisations merge and disappear. Also places where the cost to change the url is expensive, bus shelter…
A link shortener doesn't solve any of those problems