That's true. There is, however, a vast spectrum between accepting and internalizing underspecified rules, self-limiting my freedom of expression, and where you clash with your employer to the point they suggest you should leave, and yet another chasm between where they just talk and they act.
If you don't exercise your will and express yourself, you never know these limits. It's a choice all along.
If your choice is self-limiting, you'll bring it with you in the next employment. So, leaving is not a solution to that problem.