I think that the SOE have at least built up a lot of infrastructure (power, transportation) that has benefited independent companies. A lot of that would have made it much harder for non-SOE companies to be competitive.

"Due to" is a strong word, but as sct202 mentions it does seem to me like SOEs made it easier for other non-SOE companies to grow. For example, it's easier to build a bunch of cities if you have a bunch of steel manufacturing SOEs pumping out supply at a loss.

At any rate, that's beside my point, which is that (whether or not they're useful) the existence of huge SOEs by definition isn't classical capitalism, no?