No, it is not for saying what they think, it is because the women realize that he doesn't share values with her. Or that he doesn't respect her (or other women). Or because they want different things.

The classical example: a man wants just sex but say he wants a relationship in order to get sex. Sure, saying so means that only women who only want sex would stay. Then again, you can't blame the women who want a relationship for leaving and looking for someone who wants the same. The fair thing to do is to be honest and look for someone who wants the same as you.