What people consider oligarchy is actually allowing the outsourcing of governance to the elite. Corporations are disproportionately represented because they are the ones who do the most research and strategizing. The high profile victories of the post WWII era (e.g. Civil Rights, the Clean Air Act, OSHA) were achieved by grassroots groups dedicating themselves to similar levels of effort. On the other hand, modern day advocacy and political engagement prioritizes entertainment and memeyness. Even today, people achieve victories over the elite when they take civic engagement seriously like NIMBYs blocking billionaire developers.