I always try and keep self-harm in perspective, because there are degrees. In the long run, the goal is ultimately to be able to treat yourself nicely, like you matter, because you do. It's about getting to the point where you don't feel so overwhelmed by your emotions that it's necessary at all.
Whether or not the goal of stopping self-harm is a priority depends a lot on the self-harm. A person who flicks a rubber band on their wrist every so often? That wouldn't be one of my biggest priorities.
But if the person is taking a razor to their wrist? It becomes more urgent, and the reasons are multiple. First, it's a sign that they're really not coping on an emotional level - they're in a lot more emotional pain than they know how to tolerate, and that's not okay.
Second, long term, a lot of people become incredibly self-conscious about the scars. When they're in the thick of it, it's the last thing on their mind, but 5 years later when they're in a much better place, the daily reminder to themselves and the rest of the world can become a real problem.
Third, unless you're a surgeon, you don't have the training to take a razor to your wrists safely. You may not hit any major arteries, but do you know how to avoid nerve damage? Because losing control of your hand is a real disability. And that's not the goal. May not seem significant, but it's going to make your life a lot harder than it needs to be. Add to that the complications of infection, stitches, loss of blood (especially if whoops, you do hit an artery...)
Fourth, on an almost subconscious level (though for some people it's one of the goals of SH), the behaviour reinforces feelings of shame, guilt, I'm worth treating like rubbish...It's kinda like treating a hangover wirh more vodka. It's very hard to get to the point where you genuinely like yourself when you're treating yourself to SH all the time.
I'm self-harm sober for 5 months. I self-harmed for several years (not cutting, other stuff) with my T being concerned, encouraging me to learn other ways of coping, but essentially letting me do what I felt I needed to get by. Until it escalated and turned seriously dangerous. At that point, he drew the line. So perspective and prioritising will change from one situation to another. Ultimately, though, the goal is to be able to treat yourself with kindness.