I have no idea when Quincy Jones referred to. He said he met McCartney when he was 21. It wasn't till two years later that The Beatles released their first records. If, as some surmised, it was to The Beatles' early Cavern days they were raucous and messy, yet upbeat and infectious, attesting to their fan base. Listen to Cavern tapes of The Kinks. It was true of them too. There is no resemblance at all to their future hit records and live performances. Paul McCartney grew into his own shoes and consequently produced some of pop's most enduring bass lines and melodic phrases. He appears mostly based in dance hall music, 50s rock and roll, R&B, and Motown. He's always maintained a strict discipline to simplicity that can be traced throughout his songwriting and records. If that metric is below standards of criticism applied elsewhere in music then it is. Musical preferences needn't be an arbiter of musicality. I'd open a can of worms referencing primitive music styles and origins. But it's a legitimate comparison in complex rhythm, harmony, melody, and form. Some ears prefer simplicity.