> Link analytics is explicitly one of the stated use cases on Bitly, and you can even add UTM parameters automatically

This is against not in favour of your argument - it's a case of Bitly enabling users to still use other systems for tracking (UTM) while using a link shortener (as said by person you replied to), not evidence of tracking being the purpose of the link shortener.

Bitly does have their own basic analytics built in, so some people do use it for tracking, but that's still a secondary function for people who don't care enough to set up independent tracking. It's not a sale pitch of "if tracking is what you want, link shortening is the solution".

And the t.co example isn't actually useful for spam prevention, if Twitter decides that a certain URL is considered spam they can just as easily remove that link from any tweets trying to use it as they can disable a t.co. Meanwhile the t.co does add friction for users seeing whether the destination URL looks likely to be spam. I don't think I've ever heard anyone before argue that link shorteners are a good thing for fighting spam, only either bad or at best neutral.

> And the t.co example isn't actually useful for spam prevention

Don't take my word for it, that's how Twitter described it when they launched it here: https://blog.x.com/en_us/a/2012/shutting-down-spammers

From a scale perspective it also seems a lot easier to remove one redirect from happening vs. finding every Tweet that contains a certain url you want to remove.

> Additionally, we now use our link shortener (t.co) to analyze whether a tweeted link leads to malware or malicious content. This helps us prevent users from visiting malicious links and helps us shut down hundreds of thousands of abusive accounts.

You're misunderstanding the bit of that blog post that you've quoted - it only says that starting to analyse t.co links for malicious content is a good thing for reducing malicious content. It says nothing about whether that job is easier than if they started doing the analysing without having a link shortening system in place. And in fact it goes to show that spam prevention wasn't a motivating factor in their creating t.co shortener in the first place, since they only started analysing for malicious links later than they started shortening links.

It is possible that their task was made easier by having the t.co system in place - impossible to know without understanding engineering details of how Twitter and t.co work - but it's not a claim they've made publicly, nor a reason for their deciding to use shortened links.