I really don't think Rose caused the corruption. If she did, it wouldn't make sense that she'd only save a handful of her closest friends, she'd have tried to save as many of her allies as possible. Even if the goal was to wipe out gem life and leave organic life intact, she'd still have made better preparations. No, it only makes sense if Homeworld was the side that caused the corruption.

I view it more like the arms race during World War 2. Not that the rebels are in any way similar to nazis, of course, but I view it like the difference between the Axis weaponry and Allied powers weaponry. The Axis were full-on mad science: giant airships, kamikaze fighter planes, experimental gyrocopters, tanks, death rays, weapons that blow apart the enemy using sound... they had a lot of crazy ideas, and not all of them worked, but the ones that did were absolutely terrifying. The Allies, on the other hand, weren't nearly as fancy. They relied more on sheer force and reliability, using mostly good old-fashioned tanks and bomber planes and infantry and raw overwhelming numbers. And, of course, one very, very powerful, very experimental bomb, which wasn't even ready until the war was basically already over.

In this analogy, the Crystal Gems are like the Axis, and Homeworld is like the Allied powers. The CGs are more cunning and creative, but Homeworld has the advantage in force. At first, Homeworld's goal is to drive the CGs off of Earth so that they can reclaim it and resume terraforming. Then, something happens (my crack theory is that Pink Diamond is assassinated), causing Homeworld to reconsider whether Earth is worth all the effort ("I want that planet to die"). This is when it's Homeworld's turn to start developing superweapons, like the corruption and the Cluster. After a while, Homeworld begins pulling out their troops, and the CGs think they've won, until... boom. A weapon of last resort.