Hmm there are some oversimplifications of designers' work. "you're coupling how something looks to how it works" – how something looks is actually just a tiny part of designers' work. It's almost negligible, even overrated :-)

I tend to say devs program the machine, designers program the human using that machine. Most design is about understanding how brain works and "coding" a flow that the brain will execute, hopefully the way you expected.

Decoupling is a big topic. I've witnessed a lot of organisations where this decoupling was basically a complete detachment, and the result was a disaster. As a designer & developer at once, my step 1 in all teams was to build the bridge between these two sides.