People will disagree and fight endlessly over what's good and what's not. I think this is the reason:
What we commonly call "quality" is the product of two factors: Mastery x Appeal.
By "mastery" I mean how hard it is to create something similar without just copying it. Like: How hard is it to write a song like
Brothers in Arms or
Old Pigweed (one of my favorites). How hard is it to come up with such an idea, the chord sequence, the lyrics, the melody, and to play it that way? How many people would be capable of creating something similar? If the answer is: very hard/not many, then you're dealing with a high level of mastery.
By "appeal" I mean whether people will actually want to consume a work of art. Something can be created with a level of mastery, but most people still don't dig it. Arnold Schönberg's twelve-tone music would be an example. Terribly hard to compose, for sure, but not many will want to listen to it.
The problem of individuals discussing "quality" is that mastery is a rather hard factor (we'll all agree that creating
Telegraph Road is harder than creating
All My Little Ducklings) – but appeal is not. What appeals to you may not appeal to me, and vice-versa. What appeals to a few die-hard fans may not appeal to the masses, and vice-versa. As soon as you include the appeal factor in your formula, you'll automatically have people disagreeing.
At the same time, you can't just disregard the appeal factor. No one will call Arnold Schönberg the greatest composer of all time. He's just not appealing enough. Nor can you disregard the mastery factor and go by appeal (popularity) alone. If you would, Taylor Swift would be the greatest songwriter.
Most artists we will call "great" score high on
both mastery and appeal. If you ask the whole world who the greatest songwriters in pop are, the answer will be Lennon/McCartney. That's the logical result if you combine both their outstanding mastery and outstanding appeal. Taylor Swift will score lower (not enough mastery), Mark Knopfler will score lower, too (not enough appeal). That
DOESN'T automatically mean, however, that Knopfler is less of a master. Whether he is depends on his mastery score alone. And that is, in my humble opinion, just as high as Lennon's or McCartney's. I don't think it's easier to come up with a song like
Sultans of Swing than it is to come up with
She Loves You.
*End of Essay*