The sum was greater than the parts because George Martin was writing the music.
Yeah and it’s just a coincidence that since 1969, McCartney has continued to write music and Martin hasn’t never written any music of note.
George martin did write a few piano and orchestral bits here. He was a great addition musically as well as sonically. But he certainly did not write the music. There are quite a few books out there if you want to better understand what happened. Geoff Emerick’s book is very informative. He was the recordig engineer.
Martin arranged the music. Beautifully, no doubt - enough to be the fifth Beatle. But McCartney/Lennon wrote the music and lyrics.