Carbines worked like that since forever in CoH.
The only deviation from that was RETs vet1 in CoH2.
You're arguing real life.
I'm arguing reality of the game series.
I'm actually arguing that the game reflect some real life elements.
The m1 carbine being an m1 garand clone pigeon-holes the weapon into a minor variant that is not unique. Changes as proposed by donofsandeigo would make the units far more unique and interesting to use.
DAK 98k is completely different from the Wehr Grenadier 98k, so this is something easily possible for Relic to implement, especially considering the life cycle that CoH3 will have.