Well we're getting into political territory, but recently that "subsidized" seems to have swiftly changed to "threatened", so, I don't know. What you say used to be true in the past, but it's not so clear anymore.
Also: only country that ever invoked article 5 was actually the US. In that sense the opposite is true ("lots of countries have subsidized US defense"). The US "subsidy" came from the strong conviction that "US would act if we needed it", but that conviction is quickly evaporating.
On the other hand the US is running a large deficit and has a large debt - >120% of GDP - so that spend is in part other people's money.
With the foreign countries holding the most US debt being Japan, China, UK, Luxembourg and Canada.
I would also point out that you could view US bases in places like Japan or Chagos Islands as 'subsidising' local defence or it could be viewed as simple occupation.
The United States is certainly providing far more value than they’re receiving back, especially given many partners in NATO aren’t even meeting their relatively paltry obligations to defense spending.
There’s of course some benefit here but it’s largely intangible. It extends the United States’ sphere of influence and diminishes Russia’s.
I’m not saying it’s altruistic because we’re definitely acting in our own self interest and there is perceived benefit to doing these things but the consequence is still that we are spending more money on defense than we need to and other countries get to spend far less than they should be.
Yeah, let's go back to heavily armed European countries at each other's necks every couple decades... The US benefits immensely from having a stable and not terribly militaristic trading bloc.
Also: only country that ever invoked article 5 was actually the US. In that sense the opposite is true ("lots of countries have subsidized US defense"). The US "subsidy" came from the strong conviction that "US would act if we needed it", but that conviction is quickly evaporating.