Because ultimately they are in the business of marketing credit cards which they do by marketing the experience.
It's hard to quantify the value of a "good apple juice" or "good tea" but alcohol brand names are widely recognizable and searchable online making it easy to quantify: hey look with this credit card you get 50k bonus points which is 1 business class ticket to Europe which on airline XYZ means a bed, really good food, and you also get free [fill in the brand] champagne and free [fill in the brand] other alcohol.
They are also riding on the coattails of the marketing done by those alcohol brand themselves. For example, Diageo does a great job of marketing Johnnie Walker Blue as an exclusive scotch for the well-connected, well-off, in-the-know individual, with good taste (not say that's true but that's what they are aiming for) and they make sure you know it's expensive (want to impress your boss at the end of the year? get a bottle of Johnnie Walker Blue because it conveys that you spent a lot of money and it's high-end and if they aren't Scotch snobs they won't know you can get much better scotch for the same cost and they'll appreciate it a lot more than if you get an equally expensive and better scotch that has no brand recognition beyond scotch snobs).
For the bloggers, focusing on the fact that you can get Johnnie Walker Blue on your First Class experience (which you get by signing up for one of the CC they are selling you) helps you get a taste of the life of someone who regularly drinks Johnnie Walker Blue.