Both F-35B and F-35C are the variants that can liftoff from a Carrier (aka: Navy) or WASP-class Assault Ship (aka: Marines) respectively.

F-35A is the one that needs the full runway. This is a big deal, as the F35A has the best performance overall but needs the nicest conditions to launch. If the "hardest to launch" variant can be flown from a highway, then the other two models will do even better.

This is a "steelman argument". We're demonstrating the worst F35 at this job. All other variants will do even better.