To me, it sounds more like surgically replacing a fragment of your skin to get rid of a tattoo, then after some time replacing it back again to reapply the tat

To me, it sounds more like surgically replacing a fragment of your skin to get rid of a tattoo, then after some time replacing it back again to reapply the tattoo. So not exactly a walk in the park. The article seems to explicitly state that it's quite a fragile and risky operation, and that's actually why it so surprised the scientists: "[T]he process involves making a cut into DNA, it leaves the DNA somewhat vulnerable to mutations, so most cells use the process sparingly [... Studies suggest that in] mammals' brains [it happens] more than in any other area of the body — and Song’s group wanted to know why all this risky business was going on in such a vulnerable tissue as the brain."