Beatles were clearly not great individual technical musicians but extremely talented song writers (especially together) with some good production talent behind them (the fifth Beatle). Nobody went to see the Beatles for the musicianship - they could not hold a candle to the likes of Eddie Van Halen, Knopfler, Clapton, Jeff Beck, Elton John and the list goes on and on.
Beatles were like Bowie - great song writers - great melodies and highly innovative pushing their art in new directions...
I can see why professional musicians like Quincy can be frustrated by the self taught. Tom Petty could not even read music and he wrote countless hits and like the Beatles nobody went to see Tom play his guitar although Mike Campbell was supremely competent.