As a designer who codes, I know questions to ask most designers don’t. I know how to QA for our users, to ask questions, document design specs, to a degree that helps ensure users needs are accurately addressed. If you’re blessed with highly skilled devs and accessibility experts, you’re in good hands. They’re doing design work, too, that a lot of designers don’t know to document or ask questions about. As you say, confidence in the assets I have, knowing code allows me to ensure the front end is quality, provides an excellent experience to screen reader users, and ask questions to improve performance and future-prep the code.
Learning, knowing, collaborating, communicating, and embracing the path, including knowing we bring the assets, passion, and commitment to the users — that’s what I understand you’re suggesting. There is great value in knowing code, and business. Those who refuse, those are the ones I disagree with, and attempt to understand where they’re coming from, to see what I might learn, or how I might help.