This may not answer your question, but it reminds me of a time when i was talking to someone and i made some comment about how i was a pretty reasonable web developer and he quickly responded

"no, i think you misunderstand, you're a web developer when you know weird positioning bugs and javascript inconsistencies between browser releases. you probably don't want to be that person, or at least, probably not yet."

because the unspoken statement or it might have been actually spoken was "keep designing and working at a high level and find acute domain expertise elsewhere until you really want that level of knowledge."

and i think that when it comes to design, you really don't want too much domain knowledge. certainly you want some, but you don't want to be constraining your design before you've even made something. But you need it at some point, but i think, and this is the important part, that you know when you need it