I am a gun guy. The first rifle I killed a squirrel with from the top of my grain bin was our M1C when I was 8.
They ARE strictly needed, though. The class of rifle copied the form and function of the StG 44 because it worked FANTASTICALLY WELL at its goals and everyone copied it.
In typical World War 2 position assault tactics, there are x number of roles.
+Soldiers need to provide mass suppression fire to prevent reinforcement of the position(light machine gunner)
+Soldiers need to provide base fire to pin enemies (battle rifles)
+Soldiers need to perform maneuvering fire in order to advance the assault team (carbines)
+Soldiers need to spray the position in very close proximity, kill all the occupants, and take it.(shotguns and submachine guns)
The battle rifles were too big to be considered “maneuverable”, the carbines didn’t have the proper energy transfer to have stopping power in base fire , the submachine guns only had effective stopping power if you were within pistol range. Through real WW2 battle experience and analysis, it was determined that the design parameters of the battle rifles were obsolete for modern warfare in the hands of a standard rifleman, the carbines’ adaptability to being able to provide well in close cover as well as maneuvering made them indispensible tools and the submachine guns didn’t have as much punch as they were thought to have (they fired pistol rounds)
So the “assault rifle” was designed as the “One Rifle to Rule Them All.”
(Talking US; not Germany for this)
+Assault rifles have a carbine weight and profile for effective maneuvering fire. (Replaces carbine)
+Assault rifles have detachable magazines and full auto/burst capability for effective infiltration (Replaces smg, which also has detachable magazines)
+Assault rifles have semi-auto capability for effective base fire support at combat range (Replaces battle rifle)
+Assault rifles have an intermediate cartridge to optimize to all desired parameters. A “full sized” round produces too much recoil and reduces accuracy in full auto. The M1 carbine .30 round doesn’t have stopping power to full combat range, the greasers and Tommies typically fired .45 ACP (pistol ammo) and when you upsized their caliber, you’d aim for Texas and hit Oklahoma. They weren’t designed to operate with larger rounds.
This is pretty set in stone. We literally call them “assault rifles” instead of “machine carbines” because of the StG 44. Stürmgewehr means “Storm Rifle” in German, with storm as a gerund. It’s more “To Storm Rifle” or “Rifle to Storm with” aka: “Assault Rifle.”
I hope this helps