Building documented processes and standard operating procedures protects your business from depending on any single person. When processes are solid, teams work smoother and the organization survives if someone leaves.
Building processes essentially makes you and your organization lottery proof. So if you have an amazing designer who's really good at what they do and they happen to win the lottery and decide to live out their best life in the Maldives and you don't have a process in place of what they did, then whoever new designer is stepping into their shoes may not know like where to go to check all the things when they should be working on developing design who they should be communicating with. So if you have solid streamlined processes built out in place place that protects your team so they know exactly what they have to do, you're designing a roadmap for who needs to be doing what and when. And if you're adding SOP documentation as part of those processes then it gives them more context. Giving a solidly built process is going to reduce the number of questions teammates have to ask each other. It's going to allow them time to focus on what they do best.