The answer is simple, state capitalism isnt a thing, the term mean literally nothing. NEP was just socialism in a particular place at a particular time doing what needed to be done to develop the productive forces, if something like it existed today it would probably be called market socialism the term just wasnt in use then if it even existed, and also market socialism probably doesnt sound as bad as state capitalism and the whole state capitalism is something "left "communist"" came up with to insult the USSR.
Seriously state capitalism is a completely useless term, its so poorly defined it describes nothing and people should really stop using it.