Most relevant sites provide their own short urls now. All 3rd party shorteners are monetized by tracking and selling the data, so I wouldn’t be surprised nobody uses them.
I think it's bad for comments in code. If you have the full URL you could at least try to find an archived version for it on archive.org if the link shortener went away.
The archive.org link should be used in code comments imho. This ensures that the content in question has been archived, and points to the temporal snapshot.
Couldn't archive.org go away some day though? It could disappear before the original site. This seems unlikely but it's possible.
I'd rather link to the original but save it on archive.org as a backup. Of course whoever uses the broken link would have to know to go look it up on archive.org.
Well that's always a possibility. The archive.org URL usually contains the full original URL so there's no downside of using it.
In this case though, it's still just code documentation so ideally it should be somewhat possible to figure out what's going on without a link to an external site. It's just about minimizing the risk.
They are useful for transactional SMS messages when you want to remind someone of an appointment or an event. There is a character limit in SMS if you want to keep it to one message and not annoy your customers.
NSW Police need to keep making Facebook posts stating "our last SMS was not a scam" because people keep questioning them. Maybe not use bit.ly links in broadcast messages.
That’s just Twitter’s redirection proxy. It’s not people using it as a URL shortener. It is Twitter automatically linking all URLs in tweets to go via t.co for tracking.
No doubt that it's used for tracking but "clicks" on the URL could probably be measured in other on-page ways too. One additional reason is probably that if there's a spam URL detected they can just block the short URL and the problem goes away instantly.
