Going back to Twok....that whole premise and story is dependent on continuity and canon. It is a sequel to Space Seed. The following three films all lead straight from that one film. Six follows on, and is tied directly into what we see in Tng in a bunch of ways...and Tng sets up Ds9 and Voy. This is inescapable continuity making up the vast majority of the franchise.
Even when we go to Kelvin, we have whole films predicated around familiarity with the franchise as a whole. Trek, to date, is built on a level of continuity, unless you basically disregard everything bar the original 79 episodes. Even the animated series did sequels to ToS stories. Hmm...hang on...even ToS itself had recurring characters such as Mudd so...yup. Continuity everywhere. It's a bugger to wash out I guess.