It worked until it didn’t. That’s how it goes. Peace is always hard work and irrational actors (in terms of: well being of people, not necessarily aspirations of empire) can muck everything up.

Economical co-dependency is a good tool for increasing the price of going to war and making it irrational. It’s also not a zero sum game and tends to profit both sides. However, it can suck if you do it with non-democratic regimes and autocratic rulers who trample human rights.

So between France, Germany, Poland and all the other EU members it‘s keeping the continent at peace and generally does not suck because it‘s between broadly democratic nations. It also benefits each one massively and makes things possible like a common electric grid that increases reliability in general. So nearly all upside.

I do think economic cooperation with the Soviet Union and later Russia - much, much more limited than between EU members - was helpful in cooling tensions and making the world a bit safer, sure, but Russia has clearly behaved in a way that makes that no longer a good idea.