Personally, I prefer it to keep to the facts unless the story needs to deviate in order be coherent. Say, it’s a fiction about a soldier in WW1, then you shouldn’t write about how Lenin himself defeated the Germans at Verdun. What if it’s about a soviet boy in a world where, for some reason, the imperial powers looked favorably at the Soviet Union? Then by all means, tell me it’s because Lenin himself defeated the Germans at Verdun.
I got banned for “Non-Marxist answers” for explaining why Trotsky’s and Stalin’s position on internationalism weren’t the same. Those subreddits make me sad.