That's still a lot easier for some to say than for others. Until you've actually done it, it's just so much hot air. Quitting a job when you already have wealth saved from other job (or from inheritance etc.) is not the same as quitting a job when you have no savings at all. Quitting a job when you have skills and credentials that make it easy to find another is not the same as quitting a job when you have none of those things. Quitting a job when you're a citizen is not the same as quitting a job when you're dependent on your employer to retain your residency status. These are all forms of privilege. Privilege doesn't mean you're evil or weak; it just means that you might not be able to generalize your own feelings or decision making to others who lack that same privilege.

FWIW, I have quit a job for moral reasons, when I was poor and unskilled and not at all sure whether it would end up with me in the street. (Cold-calling people to sell worthless coupons.) I'll bet I could count on one hand the number of HNers more qualified to make a claim about what they would or would not do in the face of such moral qualms. And I still wouldn't generalize my experience to those who had a criminal record, less evidence of future employability, or even a different skin color.