Carole King, Joni Mitchell? But I agree.
LE
But for songwriting, no. There’s a top tier, Dylan, McCartney, Simon, the guys from ABBA, Bacharach and David. MK’s not on the top tier for me.
Man, I miss the times when songs were written by groups of people and performed by others. I think we need to define what a "songwriter" is first. A songwriter is a person who writes songs, and a song consists of melody, lyrics (poetry) and music (arrangement) for the performing of said song, which in older days was all done by different people.
If we assign points to every "all-inclusive" songwriter, we'll see how Dylan is definitely a better poet than all the rest, McCartney is a better singer and melodist, and ABBA guys are the masters of hooks and arrangement, though you can hardly give them the Nobel prize in literature, just like Dylan is not somebody I'd say is a virtuoso musician.
The strength of Mark is that he's good at literally everything: his lyrics are interesting, full of wit and wisecracks, deep and melodic, and most importantly — memorable. Not Nobel prize worthy, but worthy of analysis by smart people and singing in the shower, which is good enough in my book.
He's got plenty of decent melodies that suit his lyrics perfectly. Not to the level of the best melodists out there, not even close, but you gotta love songs like "A Night In Summer Long Ago" and other melodic material from Mark.
His arrangement skills are top-notch because it's hard to come up with covers for his songs and not make it worse. After all, he tried everything to come up with the best arrangement, best instrumentation and singer choices for his songs and there are not a lot of covers because it's really difficult to make it better or even different.
And then he tops it all off with virtuoso chops, the second voice, a secret weapon and language everybody understands — guitar licks and improvisation, tasteful solos and intricate rhythm work. Again, not on the level of the best out there, though enough to worry about (ask me how I know).
Then there's singing, producing, recording, casting musicians, stage presence, commercial success, writer's block, and a plethora of nuances where MK gets high points across the board.
If you combine ALL this, then Mark is not only in the top tier of songwriters, but in my humble opinion, might rightfully be on the very top of it as an ultimate "whole package" musician, which is proven by universal admiration of his work, praise from peers, commercial success and the existence of this very forum.