Due to recent spikes in the level of free-floating, weapons-grade stupidity, the legislatures in 33 states have secretly given The Darwin Award board of directors the right to, discreetly, promulgate this ridiculous lie.
You see, on/off ramps tend to be self-limiting in terms of max speed. Technically however, this really only applies to the curvy ones. The new rule doesn't specify tho. That's because most Darwin nominees are assumed to be fully capable of terminal mayhem all on their own w/o any assistance from say . . . physics.