Someone gave an example above where a person calling herself a trained Marxist was not accepted as evidence that she is a Marxist. Do you seriously think that editing the article to include the reference would be allowed?
Furthermore, the point is that Wikipedia has a systematic problem. Individual instances that people point out are examples. It would be impossible to fix the whole problem yourself and saying "that example doesn't count because you can fix it yourself" is just a way of ignoring examples, not dealing with the problem.
