One man's opinion.
Even the Beatles and Rolling Stones disagreed with this view.
Actually Holly was a Game-Changer in the early Rock N' Roll / Rockabilly era.
Both the Beatles and Rolling Stones, along with many others, not only recorded Holly's music but acknowledged the influence he had on their music and careers.
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No question that Holly was a game changer. But that was in ‘57. By ‘59, the game was almost over (and that’s not intended as a reference to his death).
Of course he was influential. But it was his rock songs that people noticed, not the pop ballads like “Peggy Sue Got Married” or his atrocious “True Love Ways”.
Pure rockabilly largely died when it was packaged for a mainstream audience. That’s what happened to Elvis, and that’s what was happening to Holly.
Some say he was an innovator for embracing lavish studio productions. That presupposes that overproduction is desirable. I disagree.
One can only speculate what might have been had he lived.
But I believe his career as a performer was close to its end and he would have become involved with the production and management end of the business, only to return to his roots at a later time, but then only as part of the oldies scene.