This was a problem for rifles because rifles have their highest DPS up close, own semi auto rifles and every single squad could throw both types or grenade. They were also always good on the move.
Infantry sections not the same CQC threat, so a blob of them emerging out of smoke is going to spend a while getting to the cover they need to hug to be efficient and even then, they're not fighting at their strengths. If they are using weapon upgrades they even need to be still to fire.
(On top of that, a smoke drop on your MG doesn't make you backpedal it and get some cover for it, that's on you.)
yes but USF could not spot MGs from far away, thats the main difference here. If you already got suppressed before you fired the smoke it was usually not worth it vs good micro players.
The only inf unit that could spot far for USF when rifles still had smoke nades were pathfinders, but they were never used back then because they were completely underwhelming
Germany

So it becomes stronger and more interesting over time but you have to work for it. Ofc with shared veterancy and 20-30% lower veterancy requirements than a Kubel.