Vitamin D supplementation is recommended for all Canadians, not just vegans. And Omega 3, D, and B12 are common supplement recommendations (actually backed by strong evidence) for the general population. (Although the benefits of Omega 3 supplementation for heart health has come under scrutiny, I think its anti-inflammatory effects are still pretty widely supported.)

Anyway, no need for the vitriol. Nobody is forcing you to go vegan. If it works for them, then great! It's definitely better for the planet to eat less meat, so power to them. (I eat way too many eggs to ever consider going vegan, personally.)