The "meaningful distinction" is that "assisted-opening" knives require a non-zero amount of force in the direction that the knife actually opens. Switchblades can just have a button.

The former takes a few minutes of practice to open smoothly, the latter doesn't.

There's no reason to buy an assisted-opening knife if switchblades are also available. So yes, they absolutely exist to exploit a loophole. Loopholes in laws do tend to create (often short-lived) markets.