We at languageandgrammar.com have taken some criticism for saying things like “Dictionaries are a source of common usage, not necessarily correct grammar” (see What Does the Word Dictionary Mean?), but now that the Oxford Dictionary has added thx as an entry, we’ve been proven correct.
It’s in the dictionary, so it has to be right: That’s what we often hear when a non-word (such as drug as the past tense of drag) is used. Now, thx to the Oxford dictionary, either words don’t have to include vowels, or it is true that dictionaries are a reflection of usage, not necessarily proper grammar.
We’re not saying that dictionaries serve no purpose, but it is important to remember that they are not the final word on what is gramatically correct.