My Afterthought Kev is this: There ARE Great Songs where nary a Word IS Understandable..."Louie-Louie" by the Kingsmen immediately comes to mind (Along with MANY an Instrumental Hit.)

THEN Again, there are songs like Bob Dylan's "Subterranean Homesick Blues"..(Prolly the world's First RAP Song)..where the Music's not even necessary...the WORDS set up a Rhythm that's HIT-Worthy..& Classic.

The WORDS make the Difference between a National Anthem (Ours) and a Pub Song (Where it was lifted-from-the-Brits, Originally.)

Yes, it's agreeably EASIER for a Lyricist to create a SONG if ya learn an Instrument. But "a Necessity?" Nah..(& I got 2000+ Exhibit "A"s over the last 5-6 years or so.) MOST of the Songs on the Charts HAVE a Pair Of Writers..& One did the Words/Other did The Music. Specialization. It Works!

Thanks for The Thread, Amigo!
Big Guy-Hug,
Stan