Arguably, by the standard, there are no true vegans, only those aspiring to, as best they can, lead a life free of animal products. It's so pervasive, however. Have you ever purchased a book? There's a strong chance that animal products were used in the production of its pages and binding. Have you ever used crayons? Another one.

The list of items that prevent one from being a true vegan are so very many in number that to utilize such a strict definition, particularly in light of the fact that Vegans are commonly understood (however mistaken the view) to be people who do not consume any animal-based food products.

Let's face it, if someone says "vegan diet" nearly everyone will understand what it's supposed to mean. Which means it does in fact exist. Hell, it specifically refers to "diet" as opposed to the vegan lifestyle as a whole. That's sort of a discussion ender.