It's easy to say online when it's not your career and reputation on the line. While there maybe no functional external difference in:

(a) resignation and potential replacement with someone else more willing/possibly less competent

(b) not resigning and maliciously complying

there are the matters of losing self-respect and peer credibility, opportunity costs of inability to apply effort and focus on something else more worthwhile when choosing (b), and an inability to criticize leadership.

With enough resignations and people speaking out, it adds even more to the mountain of evidence as a clear signal to reticent holdout, convincible non-ideologues.