I think your definition of scaling is a bit off here, "scaling" is mainly referring to "evolution" (or rather quality of evolution) when applied to ingame units. Oberkommando Volksgrenadiere are a perfect example of scaling, even if they do nots have that much options/abilities (Shrecks are awesome, sure): they start being rather meh (durable, but meh), and scale very good in the lategame because of vet bonuses.
While if completely agree Wehrmacht has issues in 1v1 at the moment that should be resolved, i also think that Grenadiere scale very well : their LMG is very potent, and vet bonuses are enough to make them a solid all rounder at all stages of the game (i think they should be a reference point for balance of all infantry in the game).
The way I read that makes it sound almost exactly the same man. In fact American riflemen with an M1919 or two melt infantry as fast or faster than Obersoldaten, Paratroopers are equally lethal or more so.
OKW Volksgrenadiers come with a short range grenade, a single panzershrek upgrade for 90 munitions(or lower with bulletins.) and some good vet bonuses that make them have better staying power, though early game they suck.. a lot. They don't have the combat capability to fight infantry at all. They are basically 5-man Ostruppen squads that cost 35manpower more, or 5-manpower less than a Grenadier squad.
The only reason they vet quickly is due to the fact that their panzershrek allows them to deal higher damage to vehicles with higher health pools than infantry and cost more than them. Since vet is almost directly equal to damage dealt and sustained rather than units eliminated you end up with that. Also without any other munition sinks for Volksgrenadiers and OKW as a whole. Panzershrek blobs become inevitable.
(Almost all OKW Artillery is either overpriced or too weak/broken to function, or both.)
So no, I think American rifles are probably the best scaling infantry in the game. They have almost every option open and available to them to fight the battle.
Also I'm a bit tired of people comparing the Bazooka to the Panzershrek. The Panzershrek has more damage against medium vehicles sure, but where it really shines is against the heaviest tanks in the game, which it still manages to bounce off of.(This is seen often against IS-2's)
Applied to Light-vehicles and Medium Tanks the Bazooka is almost equal to the Panzershrek in performance. With a faster reload and rate of fire as well as being a bit cheaper than a panzershrek. When playing OKW, I almost always have my volksgrens pick up a bazooka if one is dropped since it perfectly annihilates Shermans and Jacksons etc. Their armor is just so thin that they are always vulnerable to these things.