It used to be rosé and White Zinfandel, but Merlot, it seems, has also been relegated to questionable status among some oenophiles.* Merlot's fall from grace is a consequence of the growing popularity of wine overall and the assumption that Merlot is an easier, more-palatable, and less-challenging varietal specifically. If wine as a whole is more universally consumed and has thus become inadequate by itself to distinguish an elite from the masses, then certain types of wine now need to do the work as categorizing categories (to bastardize Bourdieu). In other words, since wine is popular enough that the difference between drinking wine as opposed to beer is insufficient to create distinction, differences between drinking Cabernet as opposed to Merlot are recruited to do that distinguishing. Cultural capital persists with greater granularity even as it appears to recede.
To demonstrate how media help to spread and reflect such cultural knowledge, here is a clip from the movie Sideways with Paul Giamatti playing Miles (explicit language possibly NSFW):
* - Yes, I realize that there are lots of great Merlots and that many people who take wine very seriously disagree with these judgments. I also realize that this whole discussion happened more than ten years ago.