Why add UTMs at all?
Without them, a click from a newsletter, a post on X or a paid ad all arrive as "direct" or as the bare referrer. UTMs tell your analytics exactly which link brought the visit, so you can see which posts and campaigns turned into sign-ups and revenue rather than just visits.
What a tracked short link adds
A UTM link is long and easy to mangle. A tracked link is a short link on your own domain that carries the UTMs for you and reports clicks, visits, sign-ups and revenue per link, so one link per post or newsletter tells you what each one earned. It needs a Statsy site to report to; the trial takes two minutes.