After seeing this enough times myself, I’ve come to the conclusion that “disciplines” and “experts” are simply not productive concepts at a company. People getting too attached to these things prevents a company from providing value to the customer.
Even though developers aren’t in your Venn diagram, you mentioned how helpful it was to have their contribution. I think that breaking down these barriers and embracing collaboration is the way of the future.
I hope people reading your article will be moved to follow your advice!