It's not that you wont be able to decide (yes, that would be ridiculous). It's that you will be less satisfied with the choice you make because it's harder for your to quantify the opportunity cost given so many alternatives.
I'm familiar with the Schwartz's paradox of choice, but the author is pushing it too far. Does anyone really agonize over trivial choices such as which bottle of water to buy? Is anyone really getting dehydrated and unable to chose among many alternatives? Does anyone even considers opportunity cost when making such trivial choices?
My problem is not with the paradox of choice, my problem is with the author's trivialization of it.
I found a $0.79 bottle at my local quick stop, that actually fit in my bicycle water bottle holder for my lunchtime ride. Then, of course, the quick stop closed and was torn down. Woe is me.