Smartphone cameras are ephemeral in nature. Pics can languish on those things (like mine!) for eons without seeing the light of day. They cheapen and debase the elegance of traditional studious/learned photography, but at the same time the spontaneity they allow in everyday life is unquestionably a boon that we are hopelessly entwined with. I use my smartphone for photographing things (including cameras, accessories and pricetags) while I go about doing further research, continually poking the phone's camera at whatever takes my fancy. Years ago it used to be a film camera and a LOT of film was wasted doing just those "shopping comparisons".
There should however, be a rule at weddings that smartphones should not be used to usurp the authority or presence of an official photographer who is being paid to cover the event. The impingement is potentially very troublesome, interfering with the arrangement of the couple, guests, timing, facilities etc. In other words, they should keep well out of his/her way until the official photography is over and done with.