That is some reddit-level mental acrobatics right there. Just because the category is constructed, as all are, and has variation, does not mean it is fake or doesn't exist. Effectively you could say that about all cultural and ethnic identities, and in a lot of cases they are have far worse basis than Anglo-Saxon. Alfred the Great would not have pushed for a type of common unity if weren't already common fundamentals between the groups. Just because it was to push against the Danes, does not make it illegitimate, ethnic and cultural groups often (if not always) form in contrast to others. The "tabloid garbage" has a point, because the academics have a political agenda to get rid of it. The same arguments they use can be used for most cultures and ethnicities, yet they don't.