I must admit, I agree with nearly all you said. Problem is that Ukraine was weak, and nearly without navy, and civilian ships was unable to resist to Russian navy. And Ukrainian export was blocked, as civilian ships fear to run within range of fire of Russian navy.

When Ukraine got enough weapons to force Russian ships to stay at distance, situation changed dramatically, so export was unblocked.

I think, very similar things happen during WWII.

This is not about only submarines, this is about superiority.