Large companies and large industry is the defining aspect of an industrialized society with quick travel and near-instantaneous communication across large distances.

As soon as it's possible to run efficiently a large enterprise (Thanks to the telegraph, and an extensive rail/road + automotive network), economies of scale will favor consolidation.

The Soviet Union and China are/were not and have virtually never been socialist countries - they are/were state capitalist economies.

Socialism means "corporations are owned by the people working in them", as in co-ops. State-owned corporations under brutal dictatorships are in no conceivable way "worker-owned". They all called themselves socialist just as they called themselves democratic - as in, basic propaganda.

This is very relevant in a discussion of left-wing VS right-wing economies. The Soviet Union and China are firmly in the right wing in reality, just as much as Nazi Germany or Fascist Italy were. They just had different propaganda.

A small note: state owned companies under actual Democratic societies is a more complex topic on the left-wing VS right-wing debate, that I won't go into here.

Clarification: an exact specification of socialism does not exist, but one of the consistent themes is that everything is democratized - in the sense that power rests with the people, actual power not just nominal - not necessarily by voting on everything.

The Soviet Union had big guys at the top who controlled everything from a distance, it was literally just a dictatorship (at least by the end).

Soviet Union certainly had industries, but the only large industrialists I can think of were some pre-WW2 experiments with foreign companies invited to set up shop there where it was deemed the fastest way to get access to some piece of tech and the associated know-how.

Other than that, can you give any examples of Soviet industrialists, large or otherwise?

The Soviet Union had some giant corporations with powerful leaders. The best known of these are the leaders of military industry, such as Pavel Sukhoi or Mikhail Kalashnikov, or Tupolev. Were they not industrialists? They performed the same functions as leaders of Western industry. Soviet military corporations even competed against each other for government contracts. The industrialist could also be a party functionary or minister, but for sure they had industrialists.

They were not industrialists in this sense because those people did not own the industries they managed. The state owned it, and they were hired managers who could be ousted from their position at any moment, and if that happened they immediately lost all their power and control.