Yeah Jeff, having great engineers in the studio can correct a multitude of sins. Don't get wrong, they were of course a great band.
The Beatles actually were the cutting edge of recording technology.
Yes, today, engineers can correct a multitude of sins with the digital recording and unlimited outboard effects, but when the Beatles began, it was on two track recorders, with instruments amps miced behind movable partitions, all recorded on one track, the vocals added on the other , punching in and tape splicing had its limits, and mixed on a primitive mixing board. The outboard sweeting effects were limited to reverb and tremolo.
Then Studer came out with a 4-track recorder, and later George Martin's engineer banked two Studers to create an 8-track and a 8 channel mixing board to record the SGT Pepper album. This was the beginning of modern recording, all due to the Beatles creative requests made in the studio which resulted in the first feedback, echo, flanging and backwards recordings on record.
Today tracks are unlimited, all outboard is on digital, vocals can be autotuned, single notes or drum beats can be sampled to create a "perfect" sound, and so on. Anything can be corrected, including poor musicianship.
Back in the '60's , bands had to record that "perfect" performance in the studio, because the sweetening and fixing was very, very limited.