The assertions made in Cook's article are simply easily rebutted.
The fact that people with concealed carry permits have NOT been, AFAIK, involved in mass shootings, other than as "The Good Guy" isn't an argument AGAINST CCPs, but, in fact, for them. How many mass shooters have concealed their weapons, before murdering? None of THEM had CCPs, of course.
When one looks at states with restrictive vs unrestrictive laws, it is hard to see a trend toward less gun violence UNLESS one factors in population and population density. Wyoming, with less than 600,000 people, has a 2021 gun death rate per 100,000 of 17.5 deaths, and, in 2018, had 101 gun deaths.
New Jersey, my state, with 8.9 million people has a 2021 gun death per 100K of 5.5--less than 1/3 of Wyoming's, and 485 gun deaths in 2018.
Even in my county, Essex, with 800,000 people, which includes Newark, the violent crime capital of the county and state, the gun death rate per 100,000 is 13.1-- lower than Wyoming's!
So the argument that restrictive gun laws have no effect on gun crime is hard to support in the face of such evidence...and while there are a few exceptions, you will find that in state after state these trends will hold. Yet this unproven, undocumented, un-statistically-supported assertion keeps being used again and again. It's simply an "Alternative Fact".
We can play "echo chamber" all we like but it gets us nowhere. I'm all in favor of strong, training-required, SHALL issue permitting. It doesn't have to be easy (shouldn't be), but it cannot be arbitrary as "May Issue" is, especially in my state. Hell, even the Firearm Purchase ID is far more arbitrary than it should be.
"The upper class: keeps all of the money, pays none of the taxes. The middle class: pays all of the taxes, does all of the work. The poor are there...just to scare the shit out of the middle class."--George Carlin