If the penal was close enough to satchel you, they would have wipe out your squad through sheer dps to begin with.
and this goes for just about any unit with the hand thrown grenade, except for the tommies. If the rifleman was close enough to throw a nade they were inside their optimum range. It was only a question of death by garand or death by grenade.
Penals can generally not kill full hp support weapons before they pack up and retreat, while the satchel can easily kill the entire crew if the retreat is called only a second too late.
Same goes for Riflemen dps, they're nowhere near able to finish a 3-5 man squad before the Germans can timely retreat while a grenade can instantly kill 2-4 models with ease.
The discussion wasn't about grenades winning engagements, it was about their wipe potential. And in that regard Allied grenades/satchels are just as potent as the rifle grenade.
IMO either all grenades should be considered fine, or all of them should be tweaked to be force multipliers that deal hp damage rather than killing several models at once. The rifle grenade is not an isolated case.