i don't think this is a good reason for not using yahoo, because yahoo services is much better than msn and google, and as i heard google is also collecting the personal information and msn might be doing the same thing.
Also, who cares if yahoo records our Internet activity, what will happen to us if they did that, the answer is simple noting will happen to us. moreover ur just one of hundreds of million people who are using yahoo and yahoo will not recognize u.