I don't know why he would say that but it sounds like a broad generalization. He is only marginalizing and alienating people. He sounds like he wants to make a cool crowd and the wannabe crowd from high school all over again for some reason.
Many people come from design environments or other fields or just plain interested in making a useful script.
If you want to get technical a computer was originally a human and the work was to perform mathematical calculations:
Before the development of electronic computers, the term “computer” referred to people, not machines. It was a job title, designating someone who performed mathematical equations and calculations by hand. Over the next thirty years, hundreds of women, most with degrees in math or other sciences would join those first five computers at Langley. Tucker herself helped recruit many of them, traveling to universities and women’s colleges across the South. By 1946, as the overall supervisor for Computing, Tucker presided over a vastly expanded department that had trained about 400 women and placed them in sections across the facility.  Reading, calculating and plotting data from tests in Langley’s wind tunnels and research divisions, human computers played an integral role in both aeronautical and aerospace research at the lab from the mid-1930s into the 1970s, helping it keep pace with the high output demanded by World War II and the early space race. Along with their contribution to the field, Langley’s computers also stood out for another reason: they were all women. source
So the bar for a computer, i mean programmer, I mean software engineer, I mean developer, I mean web developer has changed drastically from year to year. Some times it requires advanced math and now it requires no math or basic math.
I understand why a developer would say that. I've had known developers over the years support both sides of this argument.
I think it comes down to terminology and project requirements. If you have a project for a client and you can build that in Access, Visual Studio or other IDE and hand it over to them does that make you a developer? At the end of the day you completed the project, you made software for someone. You didn't have to know the inner workings of the .NET framework or how pixels are drawn to the screen.
This is the other point. Languages and software tools exist at all different levels, from high level languages to low level assembly language and then beneath that magic spells from Hogwarts.
I didn't know the internal workings of the frameworks or how all browsers worked or rendered pages when I started but I was making web pages.
These types of statements give rise to the imposter syndrome. I've worked with computers for 30 plus years and only around four years did that imposter syndrome go away. Mainly due to all the great resources online, a completion of knowledge of the component parts and doing large complete projects.
This gets back to the other point. The terminology. When someone says, "I'm a web developer" that is by itself a generic term and means a couple of things by context.
- the friend who added bling to their myspace page
- a student who made an HTML page for a class for their Graphic Design degree
- a person who creates blog posts and themes in Wordpress
Software is a sort of pay as you go system. You don't learn about machine learning if you are making photo gallery of your cat online or a blog on the diet of the North American albatross. You don't spend years learning the inner workings of direct x 3D API if you need to show a list of recipes online.
Even if you know the staples of "web" development, HTML, CSS, JS you could be less equipped as a web developer than if you know about a group of frameworks or IDE. Frameworks and IDE's give you information about the language. They are more about organization, documentation and building on previous work.
You have thousands of languages and each has it's own syntax and nuances and to work without it is saying, "I'm not a real carpenter if I can't build this whole house without any tools or manuals and all from memory." If all you need is a hammer to complete your work then it doesn't matter if you don't know how to use a jigsaw or how a jigsaw works.
It is almost as if he is saying, "If you can't draw the MonaLisa you are not an artist." His statement doesn't serve any purpose but to cause insecurity and drama.
I agree that learning the background and details would be good advice but there's no reason for him to suggest to break up people into groups of "real" and fake". And he is asking the wrong question, "Are you real or fake?" like 80's skateboard movie.
What it comes down to is if you can do the job.
In many job applications there is a specific group of skills that you need. Learn those. Everyone starts somewhere. ...my two cents