I agree on the specific store thing when they're saying "you must go to Pat's Fancy Spices on Old Street in Our Town." And sometimes people are saying "Hellman's" either because they got the recipe from the company in question, or because they're using it as a generic, the way people say "kleenex" to mean "tissues."
Other times it matters: there are plenty of places I can get peppercorns or thyme, but if the recipe calls for "Penzey's Singapore spice blend," it's going to be a bit of work to reconstruct without that. Many good cooks can manage it either after tasting the recipe, or get close enough from the ingredients list on an empty jar of that spice blend, but not from a television program that just says "Penzey's Singapore spice" or doesn't give you even that much of a hint. (I'm using that example because I happen to have it in my kitchen.)