Nonsense, of course it does. I just finished all six books a month ago (the first five were re-reads, AND ANOTHER THING...was new to me), and enjoyed them. Why wouldn't that series qualify? Because it's a comedy, and therefore not "serious"?
Personally I don't think Hitchhiker's Guide
worked as well in prose as it did in its original radio medium. The first book wasn't that good a novel -- it was largely just a transcription of the radio series, a succession of gags strung together. The later books, the ones that started as novels, got somewhat more substantial, but on the whole the series felt uneven to me, and I didn't care for Mostly Harmless