I don't think the ideological overhead of "cooperation is good" is a leftist one. Quite the opposite, if we qualify it down to "voluntary cooperation is good"

I don't think the ideological overhead of "cooperation is good" is a leftist one. Quite the opposite, if we qualify it down to "voluntary cooperation is good" it forms the heart of capitalism. The problem with leftism is that often it is also fine with "forced cooperation is good", and that's where it goes bad.