Copyright is not a capitalist idea, it's collectivist. See copyright in the Soviet Union, the initial bill of which was passed in 1925, right near the start of the USSR.

A pure capitalist system would have no copyright, and works would instead be protected through exclusivity (I.e. paywalls) and DRM. Copyright is intended to promote sharing by providing a period of exclusivity (temporary monopoly on a work). Whether it achieves those goals is certainly up for debate.

Long terms go against any benefit to society that copyright might have. I think it does have a benefit, but that benefit is pretty limited and should probably only last 10-15 years. I think eliminating copyright entirely would leave most people worse off and probably mostly benefit large orgs that can afford expensive DRM schemes in much the same way that our current copyright duration disproportionately benefits large orgs.