Everyone that does applications that require OS APIs, interaction with external devices, factories, embedded, air gaped desktops, care about the UI/UX of the user.
The phrasing/example in article is very web-oriented. But can you imagine interacting with your native UI toolkit as an Eve database, similar to how @browser works? Or your external devices over a protocol, similar to how @http or @mqtt works?
My point wasn't that it is a synonym for mobile. I just think there are much more web devs than regular ones AND that most of the mobile devs do (or did) web-dev (before).
And for web, not every business out there is sold to it, thankfully.
There are tons of companies on this planet that only use the web for putting their contact details and that's it, many of which actually use FB for it. All their internal software is desktop based.
I mean even most of the mobile people were web devs once...