I think a big part of the problem is that some people's power derives from their popularity, while other people's power derives from other sources.

Most of the people we try to cancel are either entertainers or politicians, because their power requires that a large number of people like them, or at least likes their work.

But CEOs at oil companies don't depend on public opinion so much.

Whereas when Whoopi Goldberg claims that the Holocaust wasn't about racism - well she's on a show that depends on positive publicity, so she's a much more vulnerable target.

Edit:

FWIW, I think the only real way we disempower oil barons and the like is by not needing them anymore. Which is to say, we invest in technologies and practices that tend to distribute power more widely overtime rather than letting it accumulate into the hands of gatekeepers.

For instance, solar panels put energy production into the hands of individual homeowners, rather than large power companies. And if we built our cities in smarter ways that didn't require as much driving, we wouldn't need as much oil for cars. It's all about distributing power broadly throughout the world, rather than letting it accumulate in a small few hotspots.