Is it correct for a ''because'' clause to act as a subject complement?

[Mwita Chacha]

I would like to know if it's accurate to complement a sentence's subject with a because adverb clause as in ''The reason she didn't turn up at the party is because her strait-faced parents denied her permission to do so,'' in which case the subordinate clause ''because her strait-faced parents denied her permission to do so'' is patently acting as the noun predicate for ''reason.'' I always have an opinion that such sentences are unreservedly imperfect, but my listening yesterday to a remarkable BBC anchor making a sentence constructed in that way has made me start to think that perhaps I have been wrong with my perception.

[Joe Carillo]

I find the use of "because" in the construction "The reason she didn't turn up at the party is because her strait-faced parents denied her permission to do so" highly objectionable because it's an obvious redundancy that repeats the sense of the phrase "the reason is" for no valid grammatical or semantic reason. People could very well say "The reason she didn't turn up at the party is that her strait-faced parents denied her permission to do so" or, even simpler and much more concise, "She didn't turn up at the party because her strait-faced parents denied her permission to do so." Even if some TV anchors have fallen into the bad habit of using "the reason...is because," my advice to both native and nonnative speakers of English is to totally avoid and shun the usage. Frankly, I can't help but feel that it's an English-language barbarism.