The Beatles took the flame of Rock and realized, like early man, that flame can be used to make things. You can forge things with it, anything you want. I think this came about for them because after The Ed Sullivan Show they went from a popular band to the biggest band in the world. They realized they were the main money earner for the record label so they could do what they wanted, and they did.
Despite George Martin, their producer’s objections, they stuck to their guns and became even more popular for it. They proved that if you have the talent, doing what you want works. The Beatles left the Rock and Roll formula far behind and started singing about deeper things and feelings. They used influences from all over the world, wrote about politics, peace and love. They wrote dirges and still wrote old school good time rock. Other talented musicians saw this and realized they didn’t want to be restrained to a formula either.
More important than that was the record companies saw what The Beatles had done, and allowed the shift from formula in their studios. Suddenly you had talented musicians writing their own stuff and trying new sounds. Sure not all of it worked but that is unimportant, because some of it did. Like in science, the experiment is the thing. Soon you had bands like Led Zeppelin putting out albums with hard English rock and California folk music on the same album! Audiences loved it.
The old rock and roll was about doing what you wanted too, it was just restrained to a handful of topics. Dating, cars, love, anything that annoyed kids parents. The Beatles took the do what you want attitude and expanded it, and now Rock and Roll has no limits. If a band has talent, the sky is the limit to what you write and play. Some bands are strictly metal, cool. Some are a rock and reggae mix, sounds good. Rock and hip hop mix, that will work. Whatever you want and The Beatles are the reason.
So let’s give it up for fifty years since the explosion that was The Beatles expanding music and our minds.
As Rick Emerson of Portland Oregon radio fame used to say, “if you are a new band, the one thing you have to realize is that The Beatles did it first, and better than you will.” Strangely he was not a big Beatles fan, he was just smart enough to realize the truth.