My intepretation of his definition is for a developer (web or other-wise) to be able to build an entire software mostly by himself, from setting up the server/database/network, designing the data models, implementing the business logic (with frameworks, APIs) and then designing the HTML/CSS/JS UI.
Just like in the context of HN, "designer" seems to mean "web designer".
I don't think this is a HN-ism. Can you point to a reference to 'full stack developer' anywhere that does not refer to web developer?
I don't claim that "Full stack developer" has been used before.
I'm not sure what you're saying. You think this term was made up by HN? Or is brand new? I can find references on the web dating from 2008 without even trying.
I'm not claiming any prior use of "Full stack developer"(TM) (haven't researched that), just that HN discussions often have a web-technology bias, where "designer" implicitly means "web designer", "low-level" means "in a VM inside a browser running on an OS running on a processor", etc.