Cas9 does not edit DNA, it cleaves DNA. What happens afterwards is up to the cell. The hype machine has ignored this fact.
One of my favorite George Church quotes: "CRISPR: some call it genome editing. I call it genome vandalism".
Base Editors can actually edit DNA, but only single bases at a time. http://www.sciencemag.org/news/2017/10/novel-crispr-derived-...
There's a big prize waiting for the person who can harness DNA repair pathways in conjunction with Cas9 to make precise, multi-base DNA edits. Lots of folks are working on that now.