A question such as this needs to be qualified - what kind of song are you discussing.
English language folk song is word based and largely narrative so the words are essential - ideally, they take precedence over the accompaniment but, unfortunately, more often than not nowadays, the music acts as a distraction.
Popular song (pop music) used to be word based, but that is no longer the case - most of the time it is impossible to follow the words of modern pop-songs anyway.
Opera is interesting in that it is a balance between words and music and can be appreciated either way - as narrative (if you are conversant with the language or the plot) or simply as beautiful music.
Jim Carroll