Music had become somewhat "sedate" after payola, blander stuff was being pushed at teens,
and they were ready to cut loose.
There were other signs that such a sound was coming, and unstoppable.
Link Wray had already introduced tthe snarling sound that would be needed in the 50's.
In 1963, "Surfin Bird" by the A -Bones, "Wipeout" by the Surfaris, and "Louie Louie" by the Kingsmen
pretty much opened the door for songs that were far wilder than the [ square] adults of the day approved of.
As far as the Beatles, there was a real anti-Beatle current at the time, Capitol was more or less in favor
of boosting the continuing popularity of the Beach Boys.
The "hair" problem for the Beatles was a great obstacle, and as kids figured out that their parents really didn't
like the Beatles, naturally their popularity increased.
The "longer hair for boys and men" war began then and it's not possible to describe now how
"unacceptable" the mop tops were then to adults.
Dick Biondi broke the Beatles early for Chicago. In most areas they were not well accepted at first.

And as soon as the parents become more accepting of the "earlier" works, say in 1966, they Beatles
started getting all heavy and introspective, so they were always a MOVING target to love/hate.