In this article about the 1970 recording of Paul's brilliant great song Uncle Albert/Admiral Halsey, studio engineer Tim Geelan from Mix Magazine said that Paul is such a great singer and that he knows that the vocals they cut over at CBS are Paul singing live right off the floor with a rhythm section into an Electro-Voice RE20 which was a relatively new mic at the time.
Also in Mark Lewisohn's excellent book which is a detailed music diary of their amazing only 8 year recording career,The Beatles Recording Sessions,where many of their recording engineers and tape operators are interviewed along with George Martin and there is a great 1987 interview with Paul in the beginning of the book,Mark explains that Paul amazingly recorded three totally different types of songs and singing styles in the same day,Yesterday,I've Just Seen A Face and his screaming rocker I'm Down and he basically said how it demonstrated how he impressively could do such different styles like that soon after the other.
Mark says in the 1965 chapter about the recordings on Monday June 14th,and Mark says,that it was a remarkable day's work,dominated by Paul McCartney and perfectly illustrating this young man's mastery of three different styles of musical composition and singing.He says what makes Paul's recording of Yesterday and he said the supreme melodic ballad all the more remarkable is that it directly followed the taping of I'm Down which Mark says is a quasi-soul/rock and roll song delivered by Paul in the most larynx-tearing,chord-shredding style imaginable.
Paul used to have a great sounding love song voice,an in between love song and rock song voice,and a great rock and even hard rock voice and he many times sang all these styles in the same song great.John was also a great singer and he had an more unique beautiful voice even when he spoke.
Paul sang great into his 50's and still good into his 50's but he sadly barely has a voice left to talk,because he kept singing rock songs live and in the studio into his 60's and now 70's.The Beatles are not only in the Song Writing Hall of Fame but the Vocal Hall of Fame too and for great valid reasons.It's really hard to believe and understand how anyone especially a genuine fan could say such nonsense.