I tend to take the view that if something is BOTH something which is a projectile device which is only designed to cause harm to something (gun, crossbow, bow, slingshot/catapult) AND is designed so that a novice can pick it up and reliably do a level of harm with minimal practice, then regulation (not a ban- some form of regulation) is appropriate.
That leaves out the low-power airguns, lower powered/home made crossbows and archery sport bows, but brings in the modern crossbows which have serious lethality due to bow design, a scope to make them easy to be accurate with, inherently consistent launch plus a simple trigger to set off.
An archery bow which needs practice, technique and strength to use with reasonable accuracy would by default not fall into scope, (although one might argue there's no need for any compound bow over 60lb draw weight- the competition limit- in UK), neither would a home made crossbow which is inherently inaccurate (compared no the modern ones) or even a longbow. Similarly, a slingshot or calapult (or even a sling-staff or a thrown rock) which takes a level of practice to relialy do harm to a targetted object would be out of scope.
I am not that surprised at the proposal really, as there have been recent cases of crossbows used to kill/injure people.
The point about intended design and projectile weapon plus ease of use in unskilled hands is I think important, as such things tend to be rather good at the intended purpose, but needing practice to achieve proper lethality with a projectile weapon has been an integral curb on misuse/wider use for centuries.
GC