I view it as a a continuity that collects individual franchises.
A franchise is a series of movies featuring the same characters or concepts, Thor The Dark World features none of the same characters or story or locations as The Incredible Hulk so how can they be the same franchise.
There's also the name factor, a franchise almost always has similiar titles with the character or franchise name in them (Spider-Man, Star Wars, Terminator, Planet/Apes, X-Men ect...) but Thor The Dark World in addition to not featuring anything Hulk has it's own title-ing separate & different from that other franchise.
If a person says they like the Captain America franchise that means they are referring to the two Cap movies, not them plus seven other non-Cap movies.
There's too many movies about different characters across the board for them all to be considered one franchise instead of a collection.
If you count them all as one then the Alien movies and Predator movies should be considered one franchise and the Tarantino movies all one franchise as they share a continuity with a number of overlapping elements. The reason they are not is that even though they share a continuity it doesn't make them all about the same characters or concepts so therefore they are viewed as individuals.
The same should happen with the various MCU movies as they each are a franchise that tells an ongoing story about one set of characters, not of all of the others too.
Basically the way I see it is Thor The Dark World isn't about Iron Man, Iron Man isn't about Captain America, Captain America The First Avenger isn't about The Incredible Hulk which isn't about Thor which isn't about Captain America and so on
Whereas every Hunger Games is about Katniss, Every Transformers about Optimus and his Autobots, every Star Trek about The crew of the Enterprise, every Star Wars about the Skywalker family and so on
If the MCU was one franchise then every movie would be about the same characters or same concept, but they aren't, they each are about different characters so each are separate franchises.