> I understand the risk of falling on the deaf ears

Always good to cast yourself as unheard in your first sentence.

> where from comes the idea that communism is the opposite (or less of) capitalism

No one said they're opposite, but no one reasonably claims they're compatible. Communists, quite simply, want means of production to be collectively owned. There's a lot of debate among communists about what collective means, but no one reasonably claims that collective means "private ownership".

> I understand the risk of falling on the deaf ears, but where from comes the idea that communism is the opposite (or less of) capitalism and not an unattainable global maximum of it instead?

From literally every piece of communist theory/philosophy ever (okay, well, “opposite” is too strong, “radical response against and rejection of the basic premsies of", though...)

I mean, communism can be envisioned as sort of the maximum endpoint of a direction of change away from feudalism where capitalism is the first step, but...