Thankfully I don't only listen to rock...
Anyhow, the words you quoted back up what I said and your post further reinforces the argument rather than diminishes it.
Radiohead being ranked at or around #1 on the charts, both on rock/pop stations as well as many indie/college stations were in a unique position to blend sounds with the potential of destroying their major fanbase and pruning it down to the diehards.
Rather than alienating folks who were in love with Pablo Honey and the Bends OK Computer comes in and does a 180, but IMO Kid A perfects it and keeps folks buying and buying. Rather than alienating MORE people start buying and appreciating their music.
They didn't invent a new style of music, but what they did do was blend multi-genres into a cohesive soundstream that was at the same time appealing to those of "haute culture" as well as your "frat boys" ready to light up another one while listening to this "awesome intense band."
There is a reason that Autechre, Tortoise, Boards of Canada et. al., are not mainstream. Sure they are mainstream for their respective genres, but they don't rock the charts. Many bands have tried to merge genres and the albums have been graded abysmal flops. In Radiohead's case, their genre-spanning albums are heralded as the greatest since Pink Floyd with some claiming they usurped their greatness.