I disagree it's clearer, because it's a spooky action at a distance. An analog are thread locals, which have the same characteristics of a dynamically scoped variable.

I've found dynamic scoping useful so few times I can count them on one hand, and while it's an intriguing feature, I think it makes a lot of sense to use a more explicit abstraction. For example, you shouldn't need dynamic scoping for overloading binary operators - you should have a more clear method that takes a context as an argument instead.

Context is external state, and it's extremely surprising when a fundamental operator like "+" modifies it.