I mean opportunities for action.I'm not sure what you mean by opportunities here. Like if the world is described to you, then certainly you can see the opportunities in it and declare actions to pursue them? Like when a crowded bar is described to you, this also implicitly includes an opportunity of punching some poor sod that happens to be in the bar, no?
When I suffer something unwanted or unexpected, the externality of the world impinging on me is very clear.
When I, an embodied and sensory being, experience the world and consider how I will act within it, the externality is experienced quite differently - my sensation of the world and my will to act in it are tightly connected. This can be in actions as trivial as walking across a room, or as complex as going into my kitchen and baking a cake.
The contrast between "opportunity" and "consequence" as I'm describing them can be illustrated simply enough: I go to make a cake, and then discover the oven won't turn on - there's a power outage! Or I go to the cupboard to get my flour, and the jar is empty - someone (maybe even me, but I forgot) used the last of the flour and didn't buy some more!
In these illustrative examples, we can see how the world - initially experienced as "ready to hand" - suddenly impinges upon us in a distinctively external way, thwarting our actions.
These aspects of how we experience the world are reasonably widely discussed in philosophy of mind and action, in literary theory, etc. RPGing can also engage with them. @TwoSix has done so, contrasting his role as player in treating the world as ready and hand and describing what his character does, and the GM's role in imposing external obstacles/frustrations so as to generate conflict.
Within the approach that TwoSix has presented, key issues of GM skill becomes what obstacles to impose, and when. Good GMing advice engages with these issues.