On a purely ideal level I agree with you (the fact that at any time someone has been fired from their job for expressing personal opinions on non-company time does not sit well with me..), but the reality of it is, how many of these people do you think know that their info is on this site and/or accessible to quite literally anyone in the world? Of the people that know that, how many of them do you think understand the implications of that openness?

This is why you lock down your privacy settings.

Yes, I understand the intention of that site and conventional thinking on the subject. Thank you for assisting in my description of an alternative