There is perhaps no rock group in history that has attracted more attention than the Beatles. Since they stepped foot in the United States and even before, they attracted huge audiences of adoring fans and people were attracted to their music obsessively.
This video gives a side-by-side comparison of Paul McCartney singing Yesterday. The first was done in 1965 and the other was in 2011. You can see that, although over 45 years separate those dates, he really has not lost a lot of his talent. People may look at the video for other reasons, some of which include conspiracies, but it really is just a testimony to his singing abilities.