I've been critical of a lot of pro-vegan propaganda, but I think that if somebody has enough money and has gaining muscle as their only goal in life then they should be able to do splendidly on a vegan diet.
Ultra-high protein consumption of 250+ grams a day, which is not practical on a vegan diet, is only supported for n00b gains, which makes sense as it's only n00bs who can gain 12+ lbs of lean mass in a year.
I'll reiterate my thoughts on the matter.
Some benefits of vegan diets:
- Avoids processed meats;
- Most junk food ends up being off limits. People are less likely to drive to the one vegan bakery in town than they are to pick up a doughnut at Tim Hortons, which I presume contains dairy.
- It's a lifestyle choice that will force the typical person to cook more and to eat in fewer restaurants.
- Probably more environmentally friendly
- Probably decreases the net misery in the world, by bypassing animal factory farming,though I admittedly have not done the integral of the (mis)-treatment of produce workers. Note that ethical animal farming exists,but is in practice a minute fraction of animal farming.
- May decrease the odds of all of the fish in the oceans getting driven to extinction.
Those benefits are not easy to dismiss.
Some costs:
- Depending on where you live, a healthy vegan diet might be more expensive. Vegan fat sources such as nuts, seeds, avocados, etc are often overpriced. Without time, money, and knowledge, a vegan diet risks bring very high in carbs.
- A lot of people have numerous relevant allergies, for example to tree nuts, coconut, etc.
- Without time, money, and/or knowledge a vegan diet might be high in soy, which might be unhealthy for non-Asian men.
- It can be anti social in some cases. For example, I am visiting someone this week and he has a deep craving for Pho. That is a Vietnamese style of soup, that is not always available as a vegan option. It's also harder to get vegan food when travelling in most non-western countries.
- Probably harder to meet the protein requirements for rapid n00b gains.
- Meat, fish, and dairy often taste better.
- Risk of deficiency of some micronutrients such as retinol, DHA, EPA, B12 ... That is only an issue because the supplement manufacturers are often dishonest, incompetent, or both. In a sane world, a vegan would be able to pay 10 cents a day for a non-scam micronutrients supplement. This can also be worked around by eating a modest amount of animal products.
I expect that most of the above will be worked out over time.