I don't think this is anywhere near true. Even without the largest 100 internet companies, it is still orders of magnitude easier to get a message out to a large audience than it has been at any other time throughout history.

You don't need a fancy Cloudflare proxy to get a message out there. A static site is easy to host and there are thousands of sites/services to choose from.

You can still stand on a soapbox, you can post a link on a wide variety of message boards, write an opinion piece for a newspaper, etc.