Are You a Full Stock Developer?

Even if you're not a full stack developer, you should be able to at least communicate with the other one. I fully agree that having domain knowledge that spans different, different areas is highly beneficial. And i think the second part of a being full stock, or denoting some one is full that kind of scares me a little bit. Or why i would never denote myself as full stock, is because there's a term like master of none, right? So if you're considered full stock, will you ever be an expert at everything? I mean, no one can be an expert in everything, right?