Why? Because it is her opinion that an owner of a semi-auto firearm is just as incompetent/ignorant as she is. Nevermind the blatant dishonesty of using the same name for machine guns and semi's, the factual errors or the multiple emotional strings she tries to pull.
Todd Vandermyde, IL NRA Lobbyist said it best in his response:
If your opinion is that semi-automatic firearms should be banned – you’re entitled to it. What you are not entitled to is the yellow journalism of trying to paint a bad range experience with an illegal firearm as the deadly weapons being talked about in the legislation. If you want to know why most gun owners and NRA members don’t trust the media, it’s because of columns like yours. Columns that play of the anti-gun extremists agenda that was set out years ago by Josh Sugarman of the Violence Policy Center (VPC).It's this kind of hack writing and outright dishonesty that keeps any sort of support for gun control outside of the foaming at the mouth fanatics. 'Journalists' (and I use the word loosely) like Marin through ignorance and/or deliberate deception mis-inform the public on this and countless other issues and people wonder why there is such head-desking levels of ignorance out there.
Her and her ilk need to find new careers.
h/t to IllinoisCarry.