To give some context here, yes, when people refer to full stack developers, they're usually referring to developers who are focused on web development, but that would also include API development, or even mobile development.
I don't think anyone thinks of full stack developers, as developers who know embedded development or compiler development, so I don't know anyone who looks down on them for not knowing these things.
> It's hard for a full stack engineer to see or admit to this because of bias, it's much easier for someone outside of web development to see it, or a more well rounded engineer to realize it.
Now obviously, the way that you put it, it's extremely difficult to say why you're wrong, because you've started by adding a bias to people who would defend it. So maybe, when you want to have a discussion about it, don't start by stating something that makes it extremely difficult to argue against it without being seen as having a bias.