I really hate that stupid show.
Besides, the opening crawl says “first major victory”. I didn’t expect the Rebel alliance to have had absolutely no success against the Empire before that, I just expected it to be smaller victories, which is what we see in Rebels.
As I stated before, it’s always mission accomplished with (almost) no casualties, smooth sailing. The victories should have been few and far between, and the very few times they succeed the sense of progress feels short-lived because of how small the victories are, and despite the seemingly hopeless outlook they refuse to give up. That IMO would have made for a more compelling show than the smooth sailing, risk averse garbage we got.
And like Neverar said, the opening crawl said first victory, plain and simple, not major.