Very few people are truly open-minded about everything. Most have a few pet issues that they absolutely take for granted, and then a bunch that they're willing to negotiate on. When they self-assess, they see only the ones they're willing to negotiate, because the others are so obvious that no one could possibly think otherwise.
Employees very quickly pick up which issues the boss will listen to, and which will make them dig in their heels. They'll challenge you only on ones where they think you'll listen. That's great if you actually are right about your deeply-held beliefs, but it's disaster if you're wrong. You won't get any push-back from your employees; they'll just leave.
Cofounders have much more skin in the game, and they will challenge you on your most deeply-held assumptions. All the fights between founders you've seen are good things; they're opportunities for the company to correct an issue that's obviously important enough that a founder is willing to raise hackles for it. Whether it leads to failure or success depends on how willing parties are to listen & compromise.