There's a lot of sleazy trickery in this industry that is nothing more than sociopathic narcissism. You can see it in the WHY "hairy arm" is used. It's used because "Wah wah, the client wants changes"

Which to be brutally frank is another way of saying "wah wah, eye dunz wunnu dew muh job!".

And that's why and where -- as you noted -- it can backfire spectacularly.

Because at the end of the day as a "designer" you cannot defend your choices with logic, reason, or facts, MAYBE the client is right and it should be changed.

The bigger trick is putting you AND the client aside and getting everyone involved caring about the ONLY thing that matters.

The end user.