Thanks for all of the replies. After thinking about it some more, I've concluded that it probably isn't realistic for one individual like myself to continue to compete against wikipedia with its thousands of "contributors", or large well-known organizations with thousands of employees. There was an opportunity to do it for a number of years, and that's one of the great things about the web, in that it potentially enables people with minority views or unusual knowledge to reach large audiences at little cost. But that has become much harder to do now that Google has de-emphasized quality, value, and relevance.
Although my sites are non-commercial, they're important to me because I try to use them to bring attention to some of society's problems and possible solutions, and to support other individuals and groups who want to do the same. In my opinion Google's current policies reinforce the status quo and make it harder for humankind to solve the problems it faces. Fortunately there are many people who will continue to fight no matter who opposes them.