My guess is the author is aiming for more general terms- that are more broadly relevant.

If you set aside strict definitions- then collectivism is no different from cooperative- and individualism from competitive.

The capitalist society emphasises 'my rights,' 'my money,' 'my x'
The only way you can have a capitalist mentality, is if you are in competition with others.

Pluralism and egalitarian is similar, pluralism is about diversity, egalitarianism is about equity across diversity.

So in short, in my small view, it is simply a naming convention the author has chosen to better fit his plans for now and future.