Quote Originally Posted by Throbert McGee View Post
If I'm not mistaken, the OCS influence also explains the long survival of the Cyrillic vowel ѣ (yat) in Russian, after it had disappeared from other Slavic languages. (And, allegedly, Bolshevik spelling reformers were eager to get rid of this letter because it "looked Biblical/religious".)
All Russian letters came from OCS, all the alphabet. Maybe except Ё that is purely native letter. On another hand all schoolchildren hated those couples of phonetically unrecognizable letters (like Е-Ѣ, И-І-Ѵ, Ф-Ѳ) which usage in each word they were forced to learn by heart.

The spelling reform was prepared before Bolsheviks, so they just applied ready-made spelling system.