I would have thought he was referring to something more steps down on the totem pole. To do iOS or Rails development you actually have to know a programming language somewhat well, especially in the case of Objective C. Or so I would have thought; perhaps I'm in unaware of IDEs and tool chains that can cover for a lack of fundamental software engineering expertise.
The variant I'd have in mind is web designers masquerading as backend system developers. That's something Node has made possible. CSS and HTML experts usually know just enough JavaScript to be dangerous--JS is table stakes these days for UI work. Node creates the illusion that they can write backend middleware, APIs and services, too. Some of them surely can, but for every one of those, I've seen ten JS "rock stars" copy-and-pasting Angular and Express code from Stack Overflow, cargo cult style, at six figures.
It was as Hydraulix said, specifically graduates of coding bootcamps. Many (not all) of those programs are very reminiscent of the "web development is hot - you can make lots of money with few qualifications!" meme that was popular in the dot-com era.
I don't actually think that web developers of today moving down the stack is all that problematic. For one, a number of them can - modern web development is a lot more intricate than it was in 1997, and if you get beyond the Bootstrap stage, it usually requires that you actually understand fundamentals of how your browser works instead of just cargo-culting some code. People who can do that usually do well in any programming language. Beyond that, Node won't really let them - it will break pretty quickly if you don't understand callbacks, async patterns, modularity, etc.
The contemporary JS world has a lot of problems, but IMHO incompetent devs isn't actually one of them. (Going out on a limb, I'd argue that all its problems actually stem from devs that are too competent in one specific area not understanding what's important and what's not in the larger context of the software industry.)
The variant I'd have in mind is web designers masquerading as backend system developers. That's something Node has made possible. CSS and HTML experts usually know just enough JavaScript to be dangerous--JS is table stakes these days for UI work. Node creates the illusion that they can write backend middleware, APIs and services, too. Some of them surely can, but for every one of those, I've seen ten JS "rock stars" copy-and-pasting Angular and Express code from Stack Overflow, cargo cult style, at six figures.