Paul McCartney said he avoided solos after his first performance with John Lennon, and Ringo Starr avoided them for his entire time with The Beatles. Lengthy instrumental solos aren’t necessarily a fundamental part of The Beatles’ sound, perhaps because half the members didn’t like them. The reasons they wanted to avoid solos were different, though.
When McCartney joined Lennon’s band, the Quarry Men, he had a chance to play a guitar solo during his first-ever performance with the band. He nailed the part during rehearsals but couldn’t get through it onstage.
“For my first gig, I was given a guitar solo on ‘Guitar Boogie,'” McCartney said, per The Beatles Anthology. “I could play it easily in rehearsal, so they elected that I should do it as my solo. Things were going fine, but when the moment came in the performance, I got sticky fingers; I thought, ‘What am I doing here?’ I was just too frightened; it was too big a moment with everyone looking at the guitar player. I couldn’t do it. (I never played a solo again until a few years ago). That’s why George was brought in.”
Source: Emma McKee/cheatsheet.com