The non-US members all have different views that must reach a consensus before any action which is precisely where the machine grinds to a halt. Which means a consensus is rarely reached. Contrasting that to the US which can bring all of its might with the whims of one leader and possible brow beating of congress to agree.

In this way, NATO/UN is interchangeable from the US point of view.

> If they all pulled their weight

This hypothetical doesn't advance the original claim. Sweden might punch well above its weight. But that hardly matters in absolute terms.