Developers could also do these processes. And they probably do, often. But they usually have their heads so far up their asses that they don't see how inscrutable this onboarding process is even for very technical users. It's like when you use one of those Linux phones and your reaction all along is "ew". Do developers not notice how bad this is? No, they don't. Some of them haven't used a good UI ever. They can't fa…
I would argue that as the one developing a system (frontend or backend) you can not perform something like that. The reason being that you already know all the small little bits, tricks, and band-aids. The only way to get proper feedback, is by putting someone completely fresh in front of the system.