Explain KV-1 in conscript support tactics then.
Or anti tank overwatch in NKVD RIFLE doctrine.
Sometimes abilities that function and have a purpose are better then slamming whatever you feel should go for the doctrine.
Easy.
KV1 plays into the original heavy "breakthrough" tank concept where a heavily armoured and slow tank is used in conjunction with infantry units to break through an enemy defensive line. In game terms, the KV1 is slow but resilient and has powerful mgs to be next to infantry, withstand AT fire and deal with MGs head on that try to delay the infantry advance. This "supports" conscripts. Conscripts also get ppsh smgs for this head on assault role, as well as repair kits for very fast repairs on the KV1 to keep the offensive going.
The anti tank overwatch ability makes perfect sense since the NKVD was not part of the army but a political branch of sorts. This makes way more sense in the context that instead of relying on their own AT like a normal Anti tank regiment would, they can quickly commission army assets for their own goals, which is translated in game as a muni ability to commission and "summon" anti tank assets from neighbouring anti tank regiments to support the NKVD commander.
You need both. An ability needs to make sense in the doctrine, like artillery in joint ops, shock troops in shock army, Guard rifles in Guard motor, and needs to be useful both in the commander context and what he gives you, as well as in general gameplay terms.
In my opinion and to loop this back to the original post, the ML20 doesn't fit the doctrine at all because it doesn't synergize with the concept or the other abilities. To that end, I proposed the T34/85 because they were an improved version of the T34/76 meant to be able to fight heavier German tanks, are still mobile to fit the aggressive "hunter" them, have good anti tank capabilities and prop up the commander's late game which is severely lacking atm since the T34/76 has no armour and little health.