I think a TRUE Vegan doesn't eat meat because it's from an animal. I'm not sure it actually has anything to do with "health" at all.
Vegetarians do eat eggs (and may possibly drink protein drinks) - which Vegans do not - I think they mostly do it as a "fad" kind of thing to appear healthy. jmo
These are also people who will - for the most part - not even be able to CONSIDER getting on a stage as far as bodybuilding goes. They have a low protein intake/higher carb intake/lower caloric intake - which amounts to skinny-fat.
Personally, I think they're all off their rockers. If you look at our teeth, they have a design that was intended for the ripping and tearing of meat, just like our "club 'em & eat 'em" ancestors. Lean meats ARE healthy - they provide iron, zinc, omega-3's, b vitamins, selenium, vitamin d and, of course - PROTEIN.
Would you want to eat an ALL protein diet? Probably not. You would definitely be setting yourself up for failure as far as binging on other things go, but when included in a balanced diet, yes, it's a good thing.
Everyone is different and responds to diets differently as far as macros go, but I think lean meats should be included in everyone's diet. Again......my opinion.