I think the difference is between organizations like square, and those that aren't.

I work at an organization like square. My manager could probably fire me. Not today, but should he desire he could manage me out, at least of his team. I have the autonomy to move elsewhere.

But I am working with ICs right now who have more organizational I influence than my manager. Certainly he decides the priorities for his direct reports, but these ICs influence the priorities for our organizing as a whole, much more strongly than my manager does. And he certainly can't fire them.

So sure, my manager is senior to me, but that's because he's senior to me. There are equally, and more, senior ICs in our org who he has to defer to in practice.