I don't this this article is very relevant in 2018. Modern Japanese websites look the same as any "hip" Western site. Take a look at Coincheck.com, for example (the exchange whose NEM just got stolen). Their landing page is the standard Bootstrap-y, scroll heavy, big icons, sparse kind of layout you would see anywhere. Every startup is like this. Even big corporations like Nintendo.co.jp manage to have modern looking websites these days. If all this cultural speculation were true, then startups would still be doing the information-dense Web 1.0 thing.

The article does make a good point about how sites were "mobile first" for Japanese feature phones. Smartphones took a while to catch on in Japan because people were already satisfied with their feature phones, but now smartphones are in full force and web design has mostly caught up with modern/trendy practices. You can see all kinds of articles about modern web stuff on Qiita.com, even translations of buzzy blogposts.

I think any speculation about cultural differences is nonsense. Overwork or trying to appear busy or neon signs or whatever doesn't make for shitty web design. Web design was bad simply because the main focus was on the feature phone (which had limited rendering capabilities) and desktop sites were an afterthought.