I agree with this specific analysis of comments on Digg - if Digg were a conversation in your front room - you wouldn't be sharing such a picture, nor making the sexist comments featured. The fact that this is on-line, allows this behaviour, the same way it's easy to write in emails things you wouldn't say to someone's face.
If Digg is to appeal to a wider audience, the site needs to find a way to focus on mainstream views and topics, or else become a virtual "back street" unwelcome to a mainstream audience.
Some of the content on Diggnation is squarely sexist too - Alex in particular making comments about other women whilst proudly advertising his engagement to Heather. Somehow passing comment on women he would like to bang, Alex seems to miss the point of being committed to someone else.