I spent a lot of time in Vermont many years ago. I'd been there a little while, blissfully unaware, before someone told me "yeah, they banned billboards here in the sixties - you didn't notice?" I hadn't consciously noticed, no, but I'd spent my time there until that comment driving around stunned at how beautiful the place was. Now I knew the reason for that (well, partial reason - billboards or not, it's a pretty part of the world, especially in summer and fall).
I've thought a lot about that billboard ban ever since, and I'm convinced it enabled a measure of calm in me.
I'm not sure how much I buy the study talked about in the OP's article - spurious correlation strikes me as a possibility - but the intuition about advertising is spot-on, I think. It'd cool if our societies had more ad-free spaces.