1. Opening themselves for a situation where you'll try to jump over their head next.
2. Giving others a reason to question their own loyalty.
>If your boss is bad at their job, you are still supposed to be able to communicate with them, work with them, and get problems resolved.
I have never seen this work. Really. If your boss doesn't like you and is not willing to put that aside, there's usually some ego and petty feelings involved and there is no good way out. You can pour endless time and energy into attempts to get it to work, and have it flushed by your boss because not letting you win is an ego thing for them. Or you can shut up, smile and pour that energy into getting the right things on your CV, networking, learning relevant technology and eventually getting a better offer and escaping.
>Working well with people is often more important than being right. Because a group of people who work well together will work mutually find the correct answers, using everyone's strengths, and helping each other grow in the process.
Nope, it's important because in a BigCo, most ambitious people don't care for being right. They care for maximizing their own income, political influence and career perspectives. And being able to navigate and communicate that will help you align your interests with theirs and get them to actually support you.