[ptttr]

The author mentions it in the first paragraph, just chooses to focus the article on the design part: "At this stage, I'm going to assume you've conducted some user research or at the very least, spoken to potential customers to test your assumptions. That way you'll be much better positioned to turn your ideas into actual design."

[superhuzza]

He added it after I made my comment on HN (I'm fairly sure it's in response to my original post):

https://web.archive.org/web/20190329103120/https://www.simon...

Anyways, it still doesn't make sense to talk to users once and then just go crazy with UI design. A lot of user research requires having prototypes (digital ones too). It's a back and forth, rather than a waterfall of talk to users, think, whip up some design.