> But a few things in an app are in fact global.

Sure, but for the most part, there is no reason for the components of the app to depend on those things being global (and a significant cost in brittleness for them to do so), so, in general, they should be passed to the objects that need them, even if they are globally consistent throughout the app.

Obviously, there are optimization reasons why you might need to avoid doing this in particular cases, but in general doing so up-front is going to be a premature optimization.