Vast majority?
Stuka zu fuss is OKW, AA HT is okw. Sturmtiger is OKW, dual HMG works, but not as good as Ost ones.
Pinplane, loiter and pin-on-demand is Ost(retreat or die), Brummbar is Ost, duel HMG works, pwerfer is all about RNG.
Soviets have demo, propaganda arty and incendiary, the 2 latter don't counter them but force retreat, katy is all about RNG.
USF have doctrinal demos
You might want to review your definition of "vast majority".
The Stuka Zu Fuss isn't for countering enemy infantry blobs, unless you catch a enemy force on retreat your not going to be hitting anything due to the way the barrage works. It's for taking out enemy support weapon spam.
Similarly, the Sturmtiger is a great blob counter, but super fucking bloody expensive at that and in a fuel starved faction it's a hard sell.
Soviets have: precision strike on both mortars, 120 autofire and barrage, demos, propaganda artillery, incendiary, Katyusha, ML-20, B4, ZiS barrage, cheap mines, ect.
Ostheer: MG42, mortar HT flames, and.....well the Brummbar and Pwerfer which are insanely rare because of T4's tech costs. The pin plane is limited to 2 doctrines, one a strafe and the other a loiter.
OKW: AA HT, Sturmtiger. Not really much else, HMG34 is insanely bad at it's job and only saving grace is the fact you can spam them. Mostly just limited to out blobbing your opponent
USF: AA HT, Scott, Sherman HE, Priest, Demos, .50 cal is fragile but ~okay~. Still your mostly limited to out blobbing your opponent like OKW