Enshittification is coming:
Beginning in the next month, when users click Bitly links or QR Codes, they may see a preview page prior to being directed to the destination URL. The page includes information about the link destination and may include advertising.
There are sometimes reason to use it. It’s shorter, so easier to remember. It’s also easier to send in text. I use a selfhosted shortener, so I can use these as dynamic links and can change the target if I need to while keeping the shortlink the same. But I agree that most don’t use it for respectable reasons.
I remember seeing a zero width shortener, which uses invisible characters to encode your link.