“Assault rifle” as a term came into being with ww2 and the introduction of fully automatic handheld weapons.
A semi automatic rifle should never be called an “assault rifle.” When people do that, they’re conflating the semi auto civilian model with the military model of things like AR15s and AK47s.
The funny thing is that full auto wouldn’t even be more dangerous. It takes like a second until you have to change your magazine, and all the shaking and muzzle climb mean you’d be shooting over the heads of anyone you were aiming at.
I rented a UMP-50 at a range, once. In burst mode at 20 yards, the first round was in the chest, the second was in the head, and the third was above the paper. Not useful except for “cover fire.”
The “assault” part of “assault rifle” refers to its ability to spray “cover fire”, which is just intended to make an enemy unit stay behind cover while the unit spraying advances. Tactical advance = assault.