Because, basically, I'm not sure I find it realistic that a woman (or man) appointed to this role would last long if she was terribly abrasive or confrontational. It would be counterproductive and distracting for everyone involved. (It serves a purpose in the book, but I prefer how the movie did it.)

Movie!Stratt creates the appearance of being very consensus-oriented. She doesn't even acknowledge the concept of power games or sexism for that matter. Authority doesn't live in confrontation or visible status markers but in the visible support and deference of everyone around her, because she made sure they are all pulling in the same direction to begin with.

She's absolutely has a lot of power but she's keeping it understated. Nothing flashy. Business casual, always moving, flat shoes, calm voice, always questions, honest answers. She's consulting the room (while leading the conversation), she is to the point but reasonably polite, she works in tandem with others, creates a sense of shared experience. "Applause!" Carl knows exactly when to jump into the conversation while deferring to her authority, "Talk to her", "Just answer the question", "I would take the three". He clearly really knows her and can pick up his end of that game. The "We don't know" chorus. The "What's the alternative" centrifuge discussion. "Thank you so much" to the underling with the coffees. Seemingly flat hierarchies.

She lets people talk and then gleans what she needs. She gives credit.

Her job is to make the decisions and take responsibility, to keep the momentum going. People are unsurprisingly okay with handing it off. She points, they march.

No one considers opposing her because they all trust her. Because they feel involved in the process. It's not hard to ask, after all, when everyone knows what it's for.

Even in the end, she has the entire team on her side when confronting Grace with his choice. Because none of it is about power or ego. Only about the mission.

The lack of future international cooperation gets her most emotional utterance out of the entire film. "Which they won't."

At every point she is pulling for a team effort. And it works. (Except one time.)