only the thompson had a rate of fire some 20 times faster than the M1 carbine. you may think you'd rather have the M1 carbine than the M1 garand and M27 but both held an advantage over the M1 be it rate of fire or penetration and range.
I would rather pack the 12 pound M1 and know I'm lethal out to 400 yards(with my marksmanship skills on unassuming targets
) and not have to worry about my bullet being deflected or stopped by heavy clothing, shrubs or other light obstacles.