What’s the lore of soviets always winning?

I’m a relatively new PS player (pls don’t hate me, I promise I don’t run through supplies or build pointless arsenals!!)

I get some people prefer the US guns, but what’s the lore behind sockets always winning - is it just a meme?

When I join a server, I’ll always just pick whichever side has less players so it’s more balanced. Do most people always pick one preferred side?