Consider also that vegetarianism was blacklisted, as 90% of the questions on this site are about vegetarianism, or at least can the questions can be applied to vegetarians.
vegetarian-diet has 5 questions tagged right now, and no wiki.
diet has 44 questions, and the wiki excerpt is:
A particular/habitual eating pattern, for example, "I'm following a raw vegan diet". This is a very general tag: please consider using more specific tags if possible.
What do you all think? I'm personally in favor of synonymizing them, but I'd like more opinions.