Agreed. We don't have a lot of UI unit tests in our software in our day job (almost none), but we have extensive tests for utility and data processing functions.
And that's pretty much the same for me in the game I'm making in my spare time. I have no unit tests for UI (it's not worth it, I can easily see when something in the UI isn't working, it's more important for me to just log the bug so I don't forget about it).
But for game logic, like verifying calculations for A.I. are happening as expected, or functions that manipulate numbers on the screen in different ways (scores, power adjustment, etc), yeah I write unit tests for those. And to the article's point, sometimes I have to significantly adjust or redo or even scrap them because I happened to think of a different mechanism and it seems to play better.
There was a long time (over about a dozen games I made) where I never bothered to write a unit test, and I still might not for a tiny game. But for my most recent bigger game (which I started a few years ago), I finally decided to write a few for some tricky numeric logic in the game, and it immediately helped me resolve a logic bug I was seeing periodically but was having a hard time pinning down the cause of it with breakpoints and logs. So I do try to do it more often for checking those things.