Sure she is, it just comes down to a point of view based on conditions.
We have had this debate before, several times. The point of view comes down to the basic reality that during Saddam's rule, and frankly because of that method of rule, there were not pockets of Islamic Extremism or Terrorist Organizations using Saddam's government for safe haven. Saddam viewed any source of leadership outside of his own as competition and a threat over being some sort of makeshift alliance. The real history here is Saddam was such a brutal ideological and paranoid dictator, and there was no real room for an association to al-Qaeda or their activities. Which would have brought even more outside attention to Iraq at the time already dealing with the US and various European nations concerning Kuwait, and dealing with the many attempts by the UN to inspect them for one reason or another. Where al-Qaeda did flourish at the time was Afghanistan, Pakistan, and other pockets in the Middle East.
That does not mean Saddam was not evil and the world is better off without those tyrants. Problem is the region subscribes to a religious ideology, of some flavor, where baked into the text is a government ideology with no aptitude for freedoms, tolerances, self determination, etc. All of those western ideological positions are difficult to take root in a culture where "authority" has such tone. In that context then removing Saddam and installing a weakened government over an even weaker military was bound to cause problems. I've said it this way before, ISIS became successful because of being able to take advantage of weakness. On one side of the border they had Syria in a multiple way long term civil war, and on the other side they had Iraq with such a weak force it became unrealistic to expect them to be able to control all of their borders. ISIS took hold, probably more concerned with the Kurds than the Iraq forces at the time.
Now I will stipulate we accelerated that weakness by pulling out of Iraq leaving behind only enough to train. A residual force might have made a difference but as Jeb Bush himself said it would have become the next South Korea. Where at our expense, we would be there indefinitely as the showing of strength that the current Iraqi government cannot or will not show. The Iraq government did not want that, and we did not obtain the necessary agreements to stay there in a manner we usually want. Namely, impunity from local law.
So, when looking at the entire picture of Iraq (not just Obama's time) then a good argument can be made that Bush 43's actions in Iraq made it possible for ISIS (or someone like them) to take charge of a large portion of the country. So much so that Obama became the 4th President... in a row... to drop a bomb on Iraq for one reason or another. If you would rather blame the entire thing on Obama to make political points against someone you do not like or agree with, so be it. But it would be devoid of the entire history of Iraq and all we did to date.