In all fairness this place is one district of one city in China. If you go to Akihabara in Tokyo you get somewhat the same thing : small stalls that sell exactly one type of product. You find your people who sell lightbulbs, or a guy who sells only capacitors.
But my point is that while that district has a bunch of that stuff, you really don't find that anywhere else (at least not in Tokyo). This is probably a similar deal.
I think you're missing the scale of this here. Being to both I can tell you that Akihabara might have specialized shops, but nothing to the level of Huaqiangbei. Neither in terms of component diversity nor in the number of shops around.
And the article also mentions the direct access to actual people from the companies/factories. This alone is what makes it absolutely unique, in my view.
The scale is definitely different, but my main point is that its very likely a local phenomenon. People might read this and assume stuff like this is everywhere in China.
I think you are right. Shenzhen is located in one of the wealthiest provinces in china, is less than an hour's train ride from Hong Kong, and is designated a special economic zone. That probably gives it several advantages over other Chinese cities.
Maybe Akihabara was once like this but it is not anymore. The shops there are clearly boutiques selling to hobbyists, filled with things like expensive vintage vacuum tubes for esoteric audio projects and not the sort of things you would want if you actually wanted to manufacture something.
I've lived in Tokyo and I am the author of this article. I have to say that the scale is completely incomparable here. Not only this, there are over 100 cities in China with a population of over 1m. There are 9 in the USA.
We used to have an area like Akihabara in NYC, from the 1920s until the '60s. It was called "Radio Row". It was displaced by eminent domain to build the World Trade center.
But my point is that while that district has a bunch of that stuff, you really don't find that anywhere else (at least not in Tokyo). This is probably a similar deal.