That's how soviets work at the moment, I support a change but it's partly an issue of the fact all of Soviets best units are gated behind commanders. But there are a good amount of blob counter commanders, the IS2 exists on more than 1 commander, and so does several other units like the t34/85. It is kinda silly however the best Howitzer in the game is on only 1 commander, but with the current relic we are dealing with I'm just thankful it exists.
While it is possible for OKW to go without a commander (not that I would ever willingly do that pak43), Ostheer needs a commander in order to stay competitive much lives soviets do.
The Jackson does the same job narrowing the meta by negating Ostheer T3. :/
The IS-2 is only in one commander since the other was never in meta and i have only seen it in old compstomps.
However shock rifle does a good job destroying all infantry with shocks, incendiary barrages, and IS-2 (and the kv-8 if you have too much fuel)
Guards mortar is mainly used because of Mark Target as well as the best mortar which indeed destroys all infantry and blobs. Soon more people will have advanced warfare with its suppressive strafe.
The main balanced Soviet tank is the KV-1, which i would like to see more of since it does a great job occupying schrek blobs with super armor and extra health. Its also tougher than the kv-8, which is a situational tank these tanks as the panther does a good job keeping it away (well, OKW's panther)