ISIS formed in the power vacuum created by the United States toppling Saddam Hussein. [0,1] So yes, the country that had its leader and military demolished was unable to combat the rise of ISIS, you're right. But pinning the failure on them is to ignore the reasons they failed to do so.
>The Middle East has been facing endemic war between Islamic sects basically for the entire history of Islam itself. The "holy wars" (call it barbarism or medievalism) being carried out in the name of Islam (by so-called "Islamic terrorists") is evidence enough that this is not actually problem of foreign policy, but a deep seated and historically pervasive domestic problem.
To collapse the rise of ISIS into the same civil wars that have been raging for the past millennia and a half is the same willful ignorance of the complex cultural history that you deride in your first paragraph. The roots of ISIS are in Wahhabism, a faction that existed mainly in Saudi Arabia. It wasn't until Roosevelt met with King Ibn Saud in 1945 (following the discovery of oil there in 1938) that this nation had any serious ambition at exporting their brand of Islam further in the middle east. Then, with the Oil Crisis of 1973, Saudi Arabia proved its political power and was able to leverage it against the United States. When it came time to expel the Soviets from Afghanistan, the United States armed the Mujahadin, a proudly Wahhabist faction.
The US being the reason that ISIS has flourished is not an opinion, it's the conclusion made over and over by analysis of historical facts.
[0]http://www.cfr.org/iraq/islamic-state/p14811 "The group that calls itself the Islamic State can trace its lineage to the aftermath of the U.S. invasion of Iraq, in 2003. The Jordanian militant Abu Musab al-Zarqawi aligned his Jama’at al-Tawhidw’al-Jihad with al-Qaeda, making it al-Qaeda in Iraq (AQI)."
http://www.thenation.com/article/what-i-discovered-from-inte... [1]"More pertinent than Islamic theology is that there are other, much more convincing, explanations as to why they’ve fought for the side they did. At the end of the interview with the first prisoner we ask, “Do you have any questions for us?” For the first time since he came into the room he smiles—in surprise—and finally tells us what really motivated him, without any prompting. He knows there is an American in the room, and can perhaps guess, from his demeanor and his questions, that this American is ex-military, and directs his “question,” in the form of an enraged statement, straight at him. “The Americans came,” he said. “They took away Saddam, but they also took away our security. I didn’t like Saddam, we were starving then, but at least we didn’t have war. When you came here, the civil war started.”
ISIS is the first group since Al Qaeda to offer these young men a way to defend their dignity, family, and tribe."