So ground based observatories have long benefited from the development of adaptive optics. That's basically where you have a small mirror that is synced to the movements of the upper atmosphere and essentially cancels out the shimmer that makes stars twinkle to the naked eye, bringing them into a sharp focus more like what you would get from a space telescope. But the tech can only achieve this feat over narrow patches sky, meaning wide field observatories were left out. I think that's what they're talking about here? You can't get much more wide field than Vera Rubin.