I agree with your point that people “from” the domain aren’t automatically equipped to start AI-building software in the domain, exactly because they often lack one of the most crucial software development skills — being able to (and having the desire to) describe a complex system with a finite set of deterministic rules.
But I don’t think we should be calling these people “domain experts”. I think we should reserve that name for the other group, for the people who truly and deeply understand the domain, the whys and whats and why nots.