>>533905712
I think it comes down to two three factors:
1) The Soviets are the default faction of the game. More default than the US or Germany. As a result, people play them and stick with them for a while. Once people are invested in a faction, even a little, it's a hard sell to swap to something new.
2) At BR I-II, their starting rifle is objectively the worst in the game. No bayonet, awful sights, low damage, awful rate of fire, awful reload. A new player who doesn't fully understand the weapon upgrade system will keep using the M1907 and doing horribly with it. The PPD-34 is also more powerful, but harder to use effectively than its contemporaries.
3) Le Rossiyan biaz memes cause people to genuinely think that Slavshits are OP in Enlisted and War Thunder. In War Thunder, the Russians don't really become particularly oppressive until top tier where they have gigantic, varied, and speculative lineups. In Enlisted, the Soviets only really hit their proper stride at BR V. Until then, their lineups are totally reliant on singular guns and have little flexibility or variety. If you wanna succeed, you have to go:
>PPD-34 spam
>PPS-43 spam
>PPSh-41 (box) spam
>PPD-40 spam
Because all your other options are mediocre or unappealing. The DP and DT are good, yeah, but to a new player they look a LOT worse than the BARs, or MG 34, or MG 42, or anything really.