There's a difference between member states pulling their weight and the org itself pulling itself together to behave as a coherent entity. If Turkey (or any member) decides to veto or drags its feet prevent any action at all from occurring, it doesn't matter. In the mean time, the aggressor is taking advantage and ransacking its way through Europe. The whole time, the individual members are waiting for the Yanks to get off their arses to unilaterally come to action. Then they can later point at how the Yanks are always doing things unilaterally and turn them into the whipping boy.

There is no veto power on article 5. It is up to the member states to organize their response or not, but they cant prevent other states to do so.

> will pull their weight

How much do they weigh in comparison to the 800lb gorilla that is the United States?

The non-US members of NATO combined are larger economically, demographically and geographically than the US is. If they all pulled their weight NATO would have (slightly) more contribution from non-US countries than from the US.

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.