If you read the article, you'll see that the method is embedded in the framework and on the ListView the method is public.I don't know exactly why we made the decisions we did my not exposing that method on the other controls, but FindControl is an abused function and people don't know how to use it properly. Wouldn't you rather have an api to get the values (because that is what you really want), rather than the thing that contains the values? Supposed your using bound fields and turned HtmlEncode and other formatting options on for your cell, do you want to use FindControl and have to figure out what sequence of methods to call to get the unformatted data back? Why not call ExtractValuesFromCell which knows how to do that?
I'm not saying don't use FindControl its just not the silver bullet that fixes all problems.
Hope this helps