It's simply a circular argument that makes no sense but confuses the general public enough to garner support for their cause.
Essentially, an 'assault weapon' is bad, because 'assault' is bad.
The features themselves are not dangerous, but are a means to determine whether a rifle is a sporting rifle or an 'assault weapon'.
They're reasonable people, I mean they're not coming after hunters, just unhinged extremist 'gun nuts' that want to kill children.
So how do you tell the difference between a hunter and an extremist?
Look at their rifle. If it has evil features, you've got yourself an extremist.
These people must be disarmed, for the kids!
This argument sounds reasonable to Joe and Joanne Public.
They don't want to stop hunters hunting, but they don't understand why someone would 'need' an 'assault weapon'. Must be to kill kids, right?
Here's the plan:
Use footage of machine guns and a scary-sounding but meaningless name for 'assault weapons' to make the public afraid and demonize gun owners.
Get 'assault weapons' banned. Not sporting rifles, just the 'assault weapons', the ones with evil features. Never mind that the two types of rifle are functionally identical, one is 'ok because it's for hunting' and the other is 'not ok because it's for slaughtering innocent people'.
When the 'assault weapons' are banned, simply point out that, actually, those 'hunting rifles' are
functionally identical to illegal 'assault weapons', so we should ban them too!
No hunter 'needs' a rifle that is just a thinly-disguised 'assault weapon' (after all, the only differences are a few
cosmetic features).
Hunters can hunt just fine with a bolt action, they don't need to 'spray bullets from the hip' to kill a deer.
Bolt action hunting rifles will then become 'high powered sniper rifles', and so on. You get the idea.
Simple
I'm from the UK, and I remember this whole thing happening there too.
Since hunting is not as popular in the UK as it is here, they didn't bother to make the distinction and simply banned ALL semiauto rifles.
They didn't even bother to give them a scary name or pretend that they were machine guns.