It's also a charge that ignores the nature of Qaddafi's "cracking down," which involved killing thousands of unarmed civilians and carrying out a program of torture, along with using the military to hunt down protesters street by street. It was enough to make the International Criminal Court issue warrants for Qadaffi's arrest for crimes against his own people before NATO imposed a no-fly zone.
With the no-fly zone in place, local forces organized as the National Transitional Council defeated Qaddafi loyalists on the ground. They held power for less than a year, conducted elections, and turned over power to an elected assembly in summer 2012. The BBC called it the first peaceful transfer of power in Libya's history. However, the new government wasn't able to bring stability, and since then levels of chaos within Libya increased, leading to a situation where two different groups claim to be the legitimate national government, several rebel groups control swaths of the country, and Libya is now a source of refugees that have destabilized other nations, as well as being a center of human trafficking.
All of which makes intervening to halt Qaddafi's attacks on protesters in the midst of the wide-spread Arab Spring seem like a terrible idea in 2016. But in 2011, with hundreds of people being shot in the streets and helicopter gunships mowing down women and children in the street, letting Qaddafi do as he pleased was an idea with limited appeal.