No, not really. Even Hanselman does not say he's well versed. It's a general understanding. I wouldn't expect a full stack developer to be able to whip out a GUI app using nothing but assembly during an interview, but I would expect them to understand that missed branch predictions thrash the instruction cache, what object files are and how a linker works, what a normalized database schema looks like, basic ipv4 networking etc. These are all wide swathes of knowledge. If someone claims they are 'full stack', what stack are they talking about? Serving web pages? If that's all it is, wouldn't 'web developer' suffice?

"The full stack developer brings the SaaS cloud to you with webscale!"

It even sounds like marketing garbage.