Thanks for writing this - it's exactly what I needed to be able to point people to. AnthonyC's comment that nutrition is multidimensional, and optimizing along any axis requires compromises in others sums up my feelings perfectly. I know the plural of anecdote isn't data, but here's my experience. Take with a pinch of salt:
For most of my adult life, I steadily reduced my consumption of animal products for ethical, health, and environmental reasons. I wasn't eating a lot of animal products when I went vegan for mostly ethical reasons 5.5 years ago. After a surprisingly steep learning curve I settled into it.
A major depressive episode prompted me to reintroduce (some) seafood, which helped, but I still spend more money and effort in return for a less healthy (physically and mentally), less varied diet than before. Overall I consider it worth some of my health and happiness to do what I consider morally right, but that's my decision to make for me.
I am baffled by the short-sightedness of people who think it's helpful to lie about this stuff and recruit people by trickery.