Not every world was like Azeroth.
Not every world had a Star Spirit of immense potential sleeping within it, nor could every world command the Pantheon's close attention and care. In fact, even after tens of millions of years of diligent work by the Titans, who enjoyed cultivating civilizations and shaping worlds, the worlds they had transformed accounted for only one percent of all the places in the Twisting Nether where life could arise.
In fact, the birth of most life and civilizations had little to do with the Titans. Like the stone-born Magnaron and the plant-born Dryads of Draenor World, they had gradually come to life through their worlds' slow evolution, and life's vigorous proliferation had given rise to all manner of strange civilizations.
The Titans called themselves the "architects of life," but this void, this universe, was simply too vast. Even these mightiest beings in the known universe could only feel at a loss when faced with its countless worlds and boundless expanse.
After Sargeras fell, a very strange idea emerged in his chaotic mind: to resist the expanding forces of the void (the Shadowlands), he had to ensure the stability of the worlds of order. Yet the Void Lords had dispatched tens of millions of Light-Dark Parasites to infect worlds that harbored Star Spirits, corrupting them before they were born and turning them into servants of the void.
The Dark Titan was the void's mortal enemy, so even as he confronted and fought it head-on, he had to focus his attention on destroying Star Spirit worlds that had already been corrupted. In that sense, Azeroth, which nurtured Elune, the Star Spirit with the greatest potential, had stood against the Dark Titan from the moment Sargeras fell.
The war between them could only end with one side falling.