The Beatles were together for a grand total of seven years. They put out 13 albums. Twenty-Seven of their songs went to #1 on the Billboard 100.   They churned out over 225 songs. You personally know the words to over 100 of them.

That comes out to:

Nearly four #1 hits per year.
2 albums per year.
Over 32 songs per year.

There has never, nor will there ever be a stronger songwriting duo than Lennon & McCartney across all genres of music.  It was a once in a millenia thing.  They knew how to write a song alone, but were even better together.

Then you go and use "Yellow Submarine" as an example of one of their songs to prove your point?  You ought to be ashamed of yourself.  They threw Ringo a bone once, and you're still holding a grudge?

What about...

Revolution
Hey Jude
Strawberry Fields
Sgt. Peppers Lonely Hearts Club Band
Here comes the sun
Eleanor Rigby
In My Life
All You Need is Love
Yesterday
We Can Work It Out
Come Together
While My Guitar Gently Weeps
Something In The Way She Moves
Lucy In The Sky With Diamonds
She Loves You (Yeah, Yeah, Yeah)
Penny Lane
Helter Skelter
Day Tripper
Get Back (My Personal Favorite)
Love Me Do
Ticket To Ride
Love Me Do
Can't Buy Me Love
Norwegian Wood
All My Loving
Paperback Writer
I Saw Her Standing There
Blackbird
With A Little Help From My Friends
You've Got To Hide Your Love Away
Lady Madonna
I Feel Fine
Twist & Shout
Eight Days A Week
Ballad of John and Yoko
Back In The U.S.S.R
Got To Get You Into My Life
Don't Let Me Down
I'm So Tired
The End
The Long & Winding Road
Carry That Weight

If they wrote 1/3 of those songs in 7 years it would be impressive enough to claim that they were one of the best songwriting duos ever.  Seven F'ing Years!

Don't forget, they all have their own songs.  George wrote and sang, So did Ringo, and obviously Paul and George.  It's unheard of, can you name another band that does that?

Now, they might not have been your flavor... but overrated?  Ugh, No.   You can literally sing everyone of those songs I listed.

I'll need a full written apology. We both know Fins is nuts...I expect more from you.  Get back JoJo.

If you doubt anything I've said... grab any Beatles album, throw on a set of cans, and you'll be able to hear exactly how good they were.  Not only were they genius, George Martin was as well.