That's really not true. You can have complete ownership of your creative process even if you work toward a brief/goal specified by someone else.

I say this as someone who has edited movie trailers for major motion pictures for 20 years. I have always been able to accomplish my own goals and by whatever means and processes I deemed important and necessary for myself, despite still needing to satisfy the client's objectives.

You do not need to give up your autonomy. The fact that you think so is troubling and speaks to a split in your psyche.

Congratulations and count yourself among the lucky. But if you cannot appreciate that things will not be that way for many employment situations then you don't know how lucky you are.