I'm not sure this is sound. When done incorrectly, any diet can have advantages and disadvantages. Many times vegans eat a lot of processes foods... Or they fail to eat particular types of nutrients. This doesn't mean that the vegan diet has disadvantages.
I'm not a proponent of veganism. I generally like the taste of milk too much (and chocolate, and yogurt, and butter). I will say that last year I cut meat out of my diet as an experiment. For background, I am a generally healthy 35 year old with a cholesterol of 220 total - with very high HDL and a very low LDL rate. Not a bad cholesterol if you consider the details. My doctor was never worried. My family has a history of heart disease, but their diets were so poor that I hesitate to even consider if it is genetic or just diet...
However, I gave up meat for 6 months and tested my cholesterol and it had dropped to 170 total with a higher proportion of HDL to LDL. My weight also dropped 10 lbs. From an average and "thin" body type, to a lean and "thin" body type. No major changes, but slight adjustments. I didn't feel any different, and I didn't have any more energy. It's been a year now. I haven't tested my cholesterol again, but I"m up for a check soon. I imagine that it'll be lower than it was. My weight hasn't went down or up following the 10 lbs drop.
I don't think I changed my whole lifestyle around by cutting out meat. I do think I might have saved myself a little time and reduced some of the stress on my body in the long term. I certainly don't think I hurt it.