If anyone with principles quit the moment a company did something bad, you'd be left with only people who are cynical and/or bad and/or sufficiently indentured to be unable to push back against management, and there would be no hope of the company ever improving.

Sure, everyone probably has their own personal line such as "will quit if my employer is declared complicit in genocide by the UN", but bad customer service seems firmly in the "better to stay and advocate doing better from the inside" category