True.
I was thinking more in terms of the new veg*ns I saw all the time on VB - lecturing longer term veg*ns, decrying how their families were murderers for eating meat (which they themselves still did a week and a half previously), etc. Sometimes they'd just disappear; a few would actually post about how they had to eat meat again for their health. One chickie in particular I remember who was a new vegan, and very militant about it. Considerably less than a year later, she was posting about the blood type diet and how her blood type necessitated her eating meat.
IMO, most of the people who disappear from veg*n boards entirely do so because they've gone back to eating meat.