Why? Why is this more "the way to go" than "hire with deliberation so you don't have to fire half your employees"? 'Cause from where I stand that hurts less people. Your "fire fast" hurts them inequitably, it hurts them much more than it does you or Your Important Business--it deprives them of their previous job, it magnifies the opportunity costs they incurred to trust you to come work for you.
Firing for "culture fit" means you fucked up. Your judgment failed. It's on you and the hurt and pain you cause is your responsibility. So it strikes me that it's being a minimum-level human being to hire carefully and with deliberation to minimize the times you fuck up and the people you hurt. Because they're people, and in every case--even the asshole ones--they deserve better than to be hurt because of your poor judgment.