And McConnell wasn't spared a second brutal blow. Bannon told interviewer Charlie Rose that at the end of the Kentucky Senator's initial meeting with the Trump transition team, McConnell insisted the president stop attacking the D.C. establishment:

"Oh, Mitch McConnell when we first met him, I mean, he was-- he was-- he-- he said, I think in one of the first meetings-- in Trump Tower with the president-- as we're wrapping up, he basically says, "I don't wanna hear any more of this 'Drain the swamp talk.' He says, "I can't-- I can't hire any smart people," because everybody's all over him for reporting requirements and-- and the pay, et cetera, and the scrutiny. You know, 'You gotta back off that."

That depiction of McConnell as being primarily protective of the status quo and his own power jives perfectly with long-held conservative complaints about his priorities and effectiveness as a Republican standard bearer on Capitol Hill. And it also fits perfectly with the reports that McConnell worked more closely with insurance company lobbyists than his fellow Republicans on the Obamacare-replacement bill.

This isn't just about being power hungry or greedy for lobbyist dollars. It's a sign of a kind of ignorance that politicians cannot afford to have... if they want to stay politicians that is. The hatred for the Washington power establishment is what propelled President Trump to victory, and that's evident in polls that show McConnell shouldering a brutal 18 percent approval rating even in his own home state.

But Bannon did not stop there. He also went after establishment Republican types who were — and still are — in the Trump administration who he says are still not loyal enough to the president. He singled out chief economic adviser Gary Cohn, who Bannon says should not have criticized President Trump so publicly following the white supremacist march and chaos in Charlottesville last month:

"You can tell him, 'Hey, maybe you can do it a better way.' But if you're gonna break, then resign. If you're going to break with him, resign. The stuff that was leaked out that week by certain members of the White House I thought was unacceptable. If you find it unacceptable, you should resign."

But perhaps the most damning indictment of the cluelessness of the Republican establishment representatives on the Trump team came from Bannon's depiction of how certain senior members of the campaign team responded to the October 2016 release of the "Access Hollywood" tapes of Donald Trump speaking crudely about women in 2005. Bannon says that then-Republican National Committee Chairman Reince Priebus was ready to throw in the towel:

"Trump went around the room and asked people the percentages he thought of still winning and what the recommendation. And Reince started off and Reince said, 'You have-- you have two choices. You either drop out right now, or you lose by the biggest landslide in American political history.'"

Bannon says that he responded by telling Trump he was still 100 percent sure Trump would win the election. And it's not so much that Bannon was right that stands out, but that Priebus was so sure it was all over. It was yet another suspicion confirmed by Bannon that the GOP leadership just isn't strongly enough behind President Trump because they still don't understand how strongly so many of their own Republican voters intend to stick by him even in the worst of times.

The fact that Priebus was still given the job of White House chief of staff despite all that is a good example of how disjointed this administration was in the beginning. Bannon describes an administration often at war with itself, with some staffers who want to keep President Trump's coalition together and others who want to, "reach out to Democrats, and let's try to work on things that we can do together."

During much of the 1980s and 90s, political pundits often wondered whether voters one day would look at the Democratic and Republican Party leadership and eventually say, "a plague on both your houses!" (To quote Mercutio in Shakespeare's "Romeo and Juliet.") That moment finally came in 2016, when a critical mass of voters sent Donald Trump to Washington not just to represent them but to punish the power structure in Washington. Because President Trump still has the capital "R" after his name, too many Republican establishment types seem to have plodded through the last 10 months under the delusion that the American people didn't reject them every bit as much as Hillary Clinton and the Democrats.

Whether they still held this delusion even after the Obamacare repeal and replacement debacle and a slew of other failures is debatable. But the Bannon interview is just the latest wake-up call to a Republican Party that should have seen the writing on the wall during President Trump's historic march through the GOP primaries.

Bannon is obviously no longer in the White House. But you don't need to be an administration insider to know that an establishment-friendly Trump agenda has no voter mandate and is probably not workable anyway. In that sense, this interview serves not only as a slap in the face to people like Speaker Ryan and Senator McConnell, but it's also a warning to those on the Trump team who think they can still go about Washington business as usual.

Commentary by Jake Novak, CNBC.com senior columnist. Follow him on Twitter @jakejakeny.

For more insight from CNBC contributors, follow @CNBCopinion on Twitter.