In 1990, they started to sequence the human genome. About a decade later, the shotgun sequencing technique was advanced enough to be used on the human genome. A few years later, it was declared complete. In 2022, it was considered to be gapless, almost 2 decades later.
All of this, plus some other discoveries, led to CRISPR and the ability to edit genes in fully formed beings rather than just a few cells. After decades of research in a number of fields.
One of the things DNA does is make protein. (If you want to look at it a certain way, all it does is determine where and when to make protein.) Part of what makes protein do the thing it does is the shape it takes. (For instance, prions are misfolded proteins that cause other proteins to misfold, and then other weird things happen, like holes in your brain.)
So we have this massively complicated process that makes slightly less complicated things that behave in a variety of ways depending on their shape, which is dependent on the myriad ways they can fold, at the molecular level. And you wonder why they haven’t done a lot when we’re still to a large degree in the data-collecting and validation portion of this massive undertaking. As for what it can lead to, I expect it will be no less revolutionary than CRISPR is and will be, but that could still be decades away.