“The song must survive being heard once.”

Memorial + wedding songs are usually heard exactly once in the context they were made for. Most listeners will not hear them attentively from start to finish. The radio-pop convention puts the most-cuttable line in the bridge or the final chorus — that convention assumes attentive listening from beginning to end. Funerals don't work that way. Weddings don't work that way. By the time the bridge arrives at a graveside, half the audience is already wiping eyes; by the time a wedding song's final chorus hits, guests are watching the couple, not the song. The lyric's strongest moment has to land BEFORE the audience's attention has drifted.