I am not leaving my $500 smartphone with anyone at a coat check, just like I would not leave my wallet at a coat check.
The blog by that photographer was interesting, but I think she's out of luck if she wants perfection at any photo shoot. The happy couples should expect that she will do the best she can, and she needs to be assertive enough to say "I'm the official photographer, please excuse me" and TAKE the best position for the shot. I understand people can leap up in front, but that might best be solved by thanking the photographer BEFORE the wedding and pointing her out, maybe asking people to kindly give her priority. That's what a friend did at her wedding and it worked just fine.
The wedding reception should definitely be a time for most people to put down the smartphones, but frankly I can easily play a game and listen to the ceremony, and in fact will be more attentive to what's going on than if I'm forced to stare at the bride and groom. The perception is that the phone is the only thing a person can pay attention to, so it seems rude, but it really isn't. Still, due to perception, no phones (or paperback books) during the ceremony is just common courtesy.
At the dinner/reception/dance? Not everyone invited to a wedding is an extrovert. Maybe you get seated beside people you don't particularly like. Maybe you need a quick break from socializing so you check email. At such events I'd probably beg off very early or not attend the after-ceremony part at all, but due to being able to retreat to the smartphone for a breather, I can make it through the evening and socialize a little bit with everyone, in short bursts.
Not to mention that texting would be preferable to talking during the dance, when music is so loud. At a friend's wedding 20 years ago, a bunch of us wanted to talk but the music was too loud, so we found an area just outside the hall to sit and visit. The groom came out and visited with us for a bit too. I suppose we could have sat inside the hall and just nodded to one another all night, since none of us enjoyed dancing. If we'd had smartphones, we could have all texted to each other in the hall, allowing us to stay in there.