What is being said is that our particular notion of names comes out of that WASP tradition. (Which, if you'll take 30 seconds to read Wikipedia, has important class and wealth connotations.) And therefore it doesn't apply perfectly to an extremely diverse society of immigrants, one with a long history of cultural, religious, and social experimentation.
It's an accident of history that a dominant strain in our culture is "protestants from the British isles". But it's still a pretty important accident. It leaves a mark. We still call that part of the country "New England", for example.
> Facebook likes to think of names as a one-to-one mapping. You have one name, and that name is how people refer to you at all times. It’s a very WASP notion of how names work, and the reality is far more complex.
Facebook, as an American company, inherited its ideas about names from mainstream American (i.e., WASP) culture. This was a poor choice, because those ideas do not also cover how some other cultures treat names. That's all this is saying. Your interpretation of this as "inflammatory" and "mischaracterizing history" is frankly baffling.
Characterizing the issue as one caused (and the inference is only protestant Anglo culture would cause) this kind of names requirement is disconnected from reality. Companies in non Anglo and non protestant places have similar and even more restrictive policies. And also this idea of names is not an Anglo concept, as it was characterized.
[1] http://www.huffingtonpost.com/good-men-project/why-its-so-ha...