I agree that there is more to scansion than syllable count, given the varying weight of syllables. When you look at Shakespeare’s writing you find most of his lines have ten syllables each. If I remember rightly, the rhyme is iambic pentameter, with five pairs of syllables per line, and the varied weighting allowed for by using dactyls, trochees and other devices that auto correct probably can’t recognise. Of course poetry doesn’t have to follow such strait jacketting, but it does work well for songs because of the inbuilt rhythm.