The Beatles had two mics out front but three people singing. Think about that for a minute. It wasn’t because they couldn’t afford another microphone.
In The Beatles Get Back documentary there wasn’t much, if any, complimenting each other as they were coming up with these incredible, historic songs. Perhaps the real affirmation was the others taking the idea and running with it. I’m sure their egos were as fragile as any but there wasn’t a constant ‘you’re doing a good job’ going around. But rather, there was a general trust (albeit fractured) of musical instinct between the members and that they would get to where they needed to go.
Not even The Beatles knew (or know) how they did what they did. For every controllable element of a career there are fifty uncontrollable elements.